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B. Davies
Published: 1 September 1972
Journal of Mathematical Physics, Volume 13, pp 1324-1329; https://doi.org/10.1063/1.1666141

Abstract:
The quantum zero‐point energy of a conducting spherical shell was first calculated by Boyer [Phys. Rev. 174, 1764 (1968)]. Because of the importance of this calculation and also of Boyer's uncertainty about the analytical dependence of the energy on the cutoff function, we have checked the calculation independently. We determine an analytic continuation of the energy function using the Mellin transform, and thereby show how an exact value of the self‐energy can be obtained from the divergent series. We also compute an approximate value of the self‐energy by extrapolating a direct numerical evaluation of the cutoff integrals. These calculations confirm Bover's result.
David W. McLaughlin
Journal of Mathematical Physics, Volume 13, pp 1099-1108; https://doi.org/10.1063/1.1666102

Abstract:
By developing an analogy between the Feynman path integral and contour integral representations of the special functions, we obtain WKB formulas for barrier penetration from a path integral. We first show that there exists for the path integral a notion of contour independence in the time parameter. We then select an appropriate contour to describe the physical situation of barrier penetration and obtain asymptotic formulas from the function space integral. The method is interpreted as a path integral derivation of the complex ray description of barrier penetration. In the last three sections we investigate several canonical problems of the theory of complex rays with these path integral techniques.
J. Beckers
Journal of Mathematical Physics, Volume 13, pp 915-918; https://doi.org/10.1063/1.1666076

Abstract:
In the study of the irreducible unitary representations [m, s] of the Poincaré group, we define an ``helicity'' spin operator through a fundamental connection between canonical and helicity bases. This operator, in covariant notation, is simply related to the well‐known Bargmann‐Wigner operator and to the canonical spin operator. Its spatial components generate an SU(2)‐algebra and coincide with the elements of the Z‐spin algebra recently proposed on different grounds by Braathen‐Foldy. The very simple arguments developed here establish in a natural way the uniqueness of this algebra when helicity representations are studied.
M. Moshinsky, T. H. Seligman, K. B. Wolf
Journal of Mathematical Physics, Volume 13, pp 901-907; https://doi.org/10.1063/1.1666074

Abstract:
In a previous paper a discussion was given of linear canonical transformations and their unitary representation. We wish to extend this analysis to nonlinear canonical transformations, particularly those that are relevant to physically interesting many‐body problems. As a first step in this direction we discuss the nonlinear canonical transformations associated with the radial oscillator and Coulomb problems in which the corresponding Hamiltonian has a centrifugal force of arbitrary strength. By embedding the radial oscillator problem in a higher dimensional configuration space, we obtain its dynamical group of canonical transformations as well as its unitary representation, from the Sp(2) group of linear transformations and its representation in the higher‐dimensional space. The results of the Coulomb problem can be derived from those of the oscillator with the help of the well‐known canonical transformation that maps the first problem on the second in two‐dimensional configuration space. Finally, we make use of these nonlinear canonical transformations, to derive the matrix elements of powers of r in the oscillator and Coulomb problems from a group theoretical standpoint.
Werner Israel, Gordon A. Wilson
Journal of Mathematical Physics, Volume 13, pp 865-867; https://doi.org/10.1063/1.1666066

Abstract:
It is shown how a new class of stationary electromagnetic vacuum fields can be generated from solutions of Laplace's equation. These fields are a stationary generalization of the static electromagnetic vacuum fields of Weyl, Majumdar, and Papapetrou, and are plausibly interpreted as exterior fields of static or steadily moving distributions of charged dust having numerically equal charge and mass densities.
Staffan Yngve
Journal of Mathematical Physics, Volume 13, pp 324-331; https://doi.org/10.1063/1.1665979

Abstract:
Using a formula derived from equations given by Furry for the normalization integral of the wavefunction corresponding to a bound state, we derive the normalization factor for the higher‐order phase‐integral approximations introduced by N. Fröman. The present treatment is based on the method developed by N. Fröman and P.O. Fröman, in which one uses exact formulas in the calculations and makes the approximations in the final stage. We particularize the resulting general formula to the case of a single‐well potential previously discussed by the present author and to the case of a double‐well potential, which has been treated in a series of papers from this institute.
James Glimm, Arthur Jaffe
Published: 1 October 1972
Journal of Mathematical Physics, Volume 13, pp 1568-1584; https://doi.org/10.1063/1.1665879

Abstract:
We introduce an inductive method to estimate the shift δE in the vacuum energy, caused by a perturbation δH of the P (φ) 2 Hamiltonian H. We prove that if δH equals the field bilinear form φ(x,t) , then δE is finite. We show that the vacuum expectation values of products of fields (Wightman functions) exist and are tempered distributions. They determine, via the reconstruction theorem, essentially self‐adjoint field operators φ(f) , for real test functions f∈ S (R 2 ) . We also bound the perturbation of the P (φ) 2 Hamiltonian by a polynomial ( P 1 (φ))(h)=δH . so long as P + P 1 is formally positive. In that case, and with ‖h‖ ∞ ≤ 1, δE is bounded by const(1 + diam supp h).
D. H. Tchrakian
Published: 1 October 1972
Journal of Mathematical Physics, Volume 13, pp 1477-1484; https://doi.org/10.1063/1.1665866

Abstract:
A prescription for decomposition into form factors of the matrix elements of totally symmetric tensor currents between (s, 0) and (s′, 0) spinor states of the incoming and outgoing particles of spins s and s′ is presented. The case of the electromagnetic current is studied in some detail, and a procedure to modify the above prescription resulting in the grouping of the form factors into Dirac‐type and Pauli‐type classes is given. Several examples are used for illustration.
J. Nuttall
Published: 1 September 1971
Journal of Mathematical Physics, Volume 12, pp 1896-1899; https://doi.org/10.1063/1.1665819

Abstract:
It is shown that second‐order multiple scattering terms lead, in some directions, to an anomalous term in the asymptotic form of the wavefunction for three free incident particles, which falls off as the inverse second power of distance. The boundary of the region in which this occurs is given, together with the form of the wavefunction near this boundary.
Marcos Moshinsky, Christiane Quesne
Journal of Mathematical Physics, Volume 12, pp 1772-1780; https://doi.org/10.1063/1.1665805

Abstract:
We show that the group of linear canonical transformations in a 2N‐dimensional phase space is the real symplectic group Sp(2N), and discuss its unitary representation in quantum mechanics when the N coordinates are diagonal. We show that this Sp(2N) group is the well‐known dynamical group of the N‐dimensional harmonic oscillator. Finally, we study the case of n particles in a q‐dimensional oscillator potential, for which N = nq, and discuss the chain of groups Sp(2nq)⊃Sp(2n)× O (q). An application to the calculation of matrix elements is given in a following paper.
Shigetoshi Katsura, Sakari Inawashiro
Journal of Mathematical Physics, Volume 12, pp 1622-1630; https://doi.org/10.1063/1.1665785

Abstract:
The lattice Green's functions of the rectangular and the square lattices I rect (a;m,n;α,β)≡ 1 π 2 [double integral operator] 0 π cos mx cos ny dx dy a−iε−α cos x−β cos y , I sq (a;m,n)≡I rect (a;m,n;1,1) are considered. The integral I rect(a, m, n; α, β) for a > α + β is evaluated and expressed in terms of the generalized hypergeometric function F 4. Expressions of I sq(a; m, n) for a > 2, a < 2, and a ∼ 2, and I rect(a; m, m; α, β) in terms of p Fp −1 are presented by the method of the analytic continuation using the Mellin‐Barnes type integral. They are useful for the understanding of the nature of the singularity and for numerical calculation. The behaviors of I sq(a; m, n) are shown in figures.
Noboru Nakanishi
Journal of Mathematical Physics, Volume 12, pp 1578-1582; https://doi.org/10.1063/1.1665776

Abstract:
A new method is proposed to discuss the exact J = 0 vector‐scalar sector solutions to the equal‐mass spinor‐spinor Bethe‐Salpeter equation for the massless‐meson exchange ladder model at the vanishing total 4‐momentum. Under the assumption that all solutions belonging to a discrete spectrum have a discrete spectral representation in the relative 4‐momentum squared, it is proved that no discrete solutions other than the solution (in the vector‐coupling case) found by Bastai, Bertocchi, Furlan, and Tonin exist in any case of the scalar, pseudoscalar, and vector couplings. As for the case of the axialvector coupling, it is shown that possible eigenvalues have to belong to one of three exponentially increasing sequences; but the existence of any solution other than Keam's one is quite unlikely. It is mathematically interesting that in the above analysis one encounters some Diophantine equations of the second degree.
Tohru Morita, Tsuyoshi Horiguchi
Journal of Mathematical Physics, Volume 12, pp 986-992; https://doi.org/10.1063/1.1665693

Abstract:
Formulas are provided which are convenient for the evaluation of the lattice Green's functions for the bcc, fcc, and rectangular lattices, at an arbitrary complex variable. The formulas involve the complete elliptic integral of the first kind with complex modulus; the integral has been found to be evaluated efficiently by the method of the arithmetic‐geometric mean, generalized for the case with complex modulus. The expansions of the lattice Green's functions around the singular points are given for the bcc and fcc lattices. These lattice Green's functions diverge at a variable. The singular points responsible for the divergences are found to form one‐dimensional lines.
Tohru Morita, Tsuyoshi Horiguchi
Journal of Mathematical Physics, Volume 12, pp 981-986; https://doi.org/10.1063/1.1665692

Abstract:
The real and imaginary parts of the lattice Green's functions for the simple cubic (actually the tetragonal), body‐centered cubic, and face‐centered cubic lattices, at the variable from −∞ to +∞, are expressed as a sum of simple integrals of the complete elliptic integral of the first kind. The results of the numerical calculations obtained with the aid of the formulas are shown by graphs.
Shigetoshi Katsura, Sakari Inawashiro, Yoshihiko Abe
Journal of Mathematical Physics, Volume 12, pp 895-899; https://doi.org/10.1063/1.1665663

Abstract:
The lattice Green's function for the simple cubic lattice I(a)= 1 π 3 [triple intergral operator] 0 π dx dy dz a+iε− cos x− cos y− cos z for a > 3 is expressed as a Mellin‐Barnes type integral. The analytic continuation gives simple and useful expressions in series for the numerical calculation of the real part I R(a) and the imaginary part I I(a) of the integral for 0 < a < 1 and 1 < a < 3. The values at a = 1, a = 0, and a=√5 are obtained exactly: I R(1) = (π/2)[Γ(5/8)Γ(7/8)]−2, I I (1)/(−i)=(√2)I R (1), and I I(0) = 3·2−11/3π−4[(Γ(1/3)]6.
Shigetoshi Katsura, Tohru Morita, Sakari Inawashiro, Tsuyoshi Horiguchi, Yoshihiko Abe
Journal of Mathematical Physics, Volume 12, pp 892-895; https://doi.org/10.1063/1.1665662

Abstract:
Physical, analytical, and numerical properties of the lattice Green's functions for the various lattices are described. Various methods of evaluating the Green's functions, which will be developed in the subsequent papers, are mentioned.
Roger Dashen, Shang‐Keng Ma
Journal of Mathematical Physics, Volume 12, pp 689-715; https://doi.org/10.1063/1.1665636

Abstract:
The role of singular forward multiparticle scattering amplitudes in S‐matrix formulas for the higher virial coefficients is studied in detail. It is shown that by means of a simple limiting process one can give a precise, unambiguous meaning to the traces over on‐shell scattering amplitudes which appear in our previous formulas for the virial coefficients. The general arguments, in which we maintain a reasonable level of rigor, are supported by explicit calculations for the third and fourth virial coefficients. Also, the angular momentum expansion used in earlier work is shown to converge.
Journal of Mathematical Physics, Volume 12, pp 606-611; https://doi.org/10.1063/1.1665627

Abstract:
Necessary and sufficient conditions are derived for the analytic extendability of a static two‐dimensional space‐time. For all allowed cases, explicit analytic extensions are determined together with their corresponding Penrose‐Carter diagrams. Extensions are classified and further discussed in terms of these diagrams, with special consideration given to the question of bifurcate Killing horizons. The application of these results to four‐dimensional relativistic space‐times is illustrated with specific examples.
, , , , , Peter Cuony, Mathieu Boccard, Grégory Bugnon, Céline Denizot, , et al.
Published: 24 May 2010
Applied Physics Letters, Volume 96; https://doi.org/10.1063/1.3432739

Abstract:
We propose the use of transparent replicated random nanostructures fabricated via nanoimprinting on glass as next-generation superstrates for thin film silicon solar cells. We validate our approach by demonstrating short-circuit current densities for p-i-n hydrogenated microcrystalline silicon solar cells as high as for state-of-the-art nanotextured ZnO front electrodes. Our methodology opens exciting possibilities to integrate a large variety of nanostructures into p-i-n solar cells and allows to systematically investigate the influence of interface morphology on the optical and electronic properties of the device in order to further improve device performance.
R. F. Keam
Journal of Mathematical Physics, Volume 12, pp 515-528; https://doi.org/10.1063/1.1665615

Abstract:
A perturbation theory is developed for the ladder approximation Bethe‐Salpeter equation that describes bound spin‐½ fermion‐antifermion systems of small total mass. A new exact analytical solution for a zero‐mass system is presented and the perturbation theory is applied to it. Some time‐reversal properties of the equation are also examined.
L. Mittag, M. J. Stephen
Journal of Mathematical Physics, Volume 12, pp 441-450; https://doi.org/10.1063/1.1665606

Abstract:
Dual transformations in many‐component Ising models in two dimensions on a square lattice are studied. The models considered include those of Ashkin and Teller and of Potts. In certain cases the dual transformation is a relation between the partition function of a lattice at high and low temperatures and can be used to determine a unique critical temperature if one exists. Dual transformations are considered both from a topological and an algebraic point of view. The topological arguments are a natural extension of those used by Onsager for the 2‐component Ising model. The transfer matrices for these models are constructed, and it is shown how the dual transformation arises in this formulation of the problem. The algebras generated by these models are investigated and provide a generalization of the spinor algebra introduced by Kaufman in the 2‐component Ising model.
Y. Ando, , K. Kasahara, Y. Kishi, K. Ueda, , ,
Published: 4 May 2009
Applied Physics Letters, Volume 94; https://doi.org/10.1063/1.3130211

Abstract:
We demonstrate electrical injection and detection of spin-polarized electrons in silicon (Si) using epitaxially grown Fe3Si/Si Schottky-tunnel-barrier contacts. By an insertion of a δ -doped n+-Si layer (1019cm3) near the interface between a ferromagnetic Fe3Si contact and a Si channel (1015cm3) , we achieve a marked enhancement in the tunnel conductance for reverse-bias characteristics of the Fe3Si/Si Schottky diodes. Using laterally fabricated four-probe geometries with the modified Fe3Si/Si contacts, we detect nonlocal output signals that originate from the spin accumulation in a Si channel at low temperatures.
Published: 1 May 2009
Journal of Applied Physics, Volume 105; https://doi.org/10.1063/1.3123763

Abstract:
This paper presents a circuit perspective on complementary metal oxide semiconductor(CMOS) limits by analyzing a standard CMOS inverter driving a capacitive load at ultralow supply voltages. While the behavior of an inverter is well understood and modeled in the superthreshold region and for sufficiently high supply voltages in the subthreshold region, the analysis at ultralow supply voltages is different. In this region of operation, the voltage levels corresponding to logic “1” and logic “0” are not V d d and G n d , respectively. We model the incomplete voltage swing and show that the minimum supply voltage for a CMOS inverter (with pull-up and pull-down devices as ideal conventional metal oxide semiconductor field effect transistors) is, indeed, 2 k T / q ln 2 . The novelty of this approach lies in the fact that it gives an explicit mathematical relationship between the supply voltage and a measure of distinguishability of the binary states defined in terms of the expected voltage swing. The analysis shows that the minimum supply voltage corresponds to the state when the two states become completely indistinguishable. Further, we obtain a relationship between the switching energy and robustness of CMOS inverters and interconnects, valid for the entire range of supply voltages. This analysis also shows that a minimum supply voltage of 2 k T / q ln 2 may not correspond to the fundamental energy dissipation of k T ln 2 .
H. X. Guo, B. Yang, L. Chen, Y. D. Xia, , , J. Yin
Published: 10 December 2007
Applied Physics Letters, Volume 91; https://doi.org/10.1063/1.2825273

Abstract:
Resistive switching devices with a sandwich structure Ag(AgI)0.5(AgPO3)0.5Pt were fabricated on silicon(001) wafer by using the pulsed laser deposition method and the focused ion beam nanofabrication technique. (AgI)0.5(AgPO3)0.5 films deposited at room temperature show a nanocrystal structure and the composition of the films was identified by using x-ray photoelectron spectroscopy. The current-voltage characteristics of the Ag(AgI)0.5(AgPO3)0.5Pt memory units show good switching behaviors. The ratio of the conductance between the “ON” state (high conductance) and the “off” state (low conductance) reaches 1×106 . The ON and OFF states can be effectively written, read, and erased up to 4×105 scanning cycles by using a set of voltage pulses with an amplitude less than 3V . It also could be observed that the time for the writing and erasing operations could be less than 150ns . The switching mechanism of the Ag(AgI)0.5(AgPO3)0.5Pt memory devices was ascribed to the possible formation and dissolution of Ag filaments in (AgI)0.5(AgPO3)0.5 films induced by the applied electrical pulses with different polarities.
Published: 10 December 2007
Applied Physics Letters, Volume 91; https://doi.org/10.1063/1.2823577

Abstract:
Noise in pentacene thin film transistors has been measured as a function of device thickness from well above the effective conduction channel thickness to only two conducting layers. Over the entire thickness range, the spectral noise form is 1 ∕ f , and the noise parameter varies inversely with gate voltage, confirming that the noise is due to mobility fluctuations, even in the thinnest films. Hooge’s parameter varies as an inverse power law with conductivity for all film thicknesses. The magnitude and transport characteristics of the spectral noise are well explained in terms of percolative effects arising from the grain boundary structure.
Published: 10 December 2007
Applied Physics Letters, Volume 91; https://doi.org/10.1063/1.2822420

Abstract:
The statistics of electrical breakdown field ( E bd ) of Hf O 2 and Si O 2 thin films has been evaluated over multiple length scales using macroscopic testing of standardized metal-oxide-semiconductor ( Ti N ∕ Si O 2 ∕ Si ) and metal-insulator-metal ( Ti N ∕ Hf O 2 ∕ Ti N ) capacitors ( 10 − 2 mm 2 – 10 μ m 2 area) on a full 200 mm wafer along with conductive-atomic-force microscopy. It is shown that E bd follows the same Weibull distribution when the data are scaled using the testing area. This overall scaling suggests that the defect density is ∼ 10 15 cm − 2 and E bd is ∼ 40 MV ∕ cm for nanometer-length scales; as such, breakdown in these materials is most likely initiated by bond breaking rather than punctual defects.
Published: 26 March 2007
Applied Physics Letters, Volume 90; https://doi.org/10.1063/1.2717532

Abstract:
The lateral spatial resolution (LSR) in two-photon induced polymerization was improved to 80 nm by using an anthracene derivative (9,10-bis-pentyloxy-2,7-bis[2-(4-dimethylamino-phenyl)-vinyl]anthracene (BPDPA)) as a highly sensitive and efficient photoinitiator. Photocurable resin containing 0.18 mol % BPDPA exhibited a low polymerization threshold of 0.64 mW at 800 nm . Theoretical calculations showed that the LSR can be increased by reducing the laser power, indicating that the LSR could be improved using more sensitive initiators in the future.
, , Ken-Ichi Ueda, Hideki Yagi, Takagimi Yanagitani, Alexander A. Kaminskii
Published: 26 March 2007
Applied Physics Letters, Volume 90; https://doi.org/10.1063/1.2717519

Abstract:
Laser-diode pumped nearly diffraction-limited beam quality ( M 2 < 1.05 ) , high peak power, subnanosecond passively Q -switched Yb : Y 3 Al 5 O 12 ceramic miniature laser with Cr 4 + : Y 3 Al 5 O 12 ceramic as saturable absorber has been achieved. The slope efficiency is as high as 36% for 80% initial transmission of Cr 4 + : Y 3 Al 5 O 12 ceramic. The pulse width of 335 ps and peak power of over 150 kW at repetition rate of 5 kHz were obtained. Laser oscillates at single-longitudinal-mode oscillation and wide-separated multilongitudinal-mode oscillation due to the combined etalon effect of the Cr 4 + : YAG thin plate and thin glass plate as output coupler.
, , E. Kuokštis, K. Liu, , J. P. Zhang,
Published: 26 March 2007
Applied Physics Letters, Volume 90; https://doi.org/10.1063/1.2717145

Abstract:
A set of Al0.35Ga0.65NAl0.49Ga0.51N multiple quantum wells (MQWs) with fixed barrier width and well widths varying from 1.65to5.0nm has been grown by metal-organic chemical vapor deposition. Carrier dynamics in the MQWs were studied using time-resolved photoluminescence (PL) spectroscopy and light-induced transient grating (four wave mixing) technique. The authors observed that the lifetime of nonequilibrium carriers (excitons) increases with decreasing well width and interpreted the effect by stronger localization preventing their migration to nonradiative recombination centers. Meanwhile the radiative decay time is also influenced by screening of the built-in electric field, which spatially separates the electrons and holes. It is shown that this effect affects the initial part of PL intensity decay after pulsed excitation. It becomes more pronounced with increase in the initial carrier density but saturates when the carrier density is high enough to completely screen the built-in electric field. The screening effect on PL decay is stronger in wider quantum wells.
R. R. Gubaĭdullin, , R. M. Rakhmatullin, S. Sen
Published: 15 March 2007
Journal of Applied Physics, Volume 101; https://doi.org/10.1063/1.2713351

Abstract:
Pulsed electron paramagnetic resonance(EPR)spectroscopy has been used to study the influence of codoping with N and/or F on the clustering of Er 3 + ions in vitreous SiO 2 . Measurements of echo-detected EPR, spin-lattice and phase memory relaxation times, and electron spin-echo envelope modulation (ESEEM) were made in the X band. Er-N, Er-F, and Er-N-F codoped glasses show clear evidence of clustering of Er 3 + ions at concentration levels ranging between 6.67 × 10 18 cm − 3 and 6.67 × 10 19 cm − 3 . However, the relatively long phase memory relaxation time and the observability of ESEEM in the Er-N-F codoped glass strongly indicate that combined codoping with N and F is more effective in homogenization of the spatial distribution of Er 3 + ions in vitreous SiO 2 , although, the structural mechanism remains unclear. The ESEEM results provide evidence in favor of the presence of N in the vicinity of the Er 3 + ions in Er-N-F codoped vitreous SiO 2 .
, L. J. A. Koster,
Published: 26 March 2007
Applied Physics Letters, Volume 90; https://doi.org/10.1063/1.2711534

Abstract:
In organic semiconductors the recombination mechanism is of the Langevin type, controlled by the mobility of the charge carriers. As a result, in organic solar cells the mobility simultaneously controls both the carrier extraction and the losses via carrier recombination. The authors demonstrate that the balance between carrier losses by extraction and by recombination leads to a distinct optimum in the carrier mobility with regard to the efficiency of organic solar cells. For low mobilities recombination losses limit the performance, whereas the efficient extraction at high mobilities leads to a reduction of the open-circuit voltage.
Dae-Hwang Kim, Florian Merget, Michael Först, Heinrich Kurz
Published: 15 March 2007
Journal of Applied Physics, Volume 101; https://doi.org/10.1063/1.2710440

Abstract:
Switching dynamics associated with reset and set operations of vertical phase change random access memory (PCRAM) cells are studied using a three-dimensional simulation model. Based on a finite difference method, the numerical algorithm simulates the electrical, thermal, and phase change dynamics in the PCRAM device during switching operations taking into account electrical and thermal percolation characteristics of the phase changematerial. Toward a better understanding of switching operations and the optimization of cell designs, the obtained simulation results provide unprecedented insight into temporally and spatially resolved kinetics of device temperature, current densities, and phase transitions. Threshold conditions for reset and set operations are identified in close agreement to existing experimental data, and the scaling ability of the investigated vertical PCRAM cell design to a minimum feature size of at least 40 nm is demonstrated.
, I. Vrejoiu, G. Le Rhun,
Published: 15 March 2007
Journal of Applied Physics, Volume 101; https://doi.org/10.1063/1.2560217

Abstract:
Photovoltaic properties of the metal-ferroelectric-metal structures, having SrRuO3 metal oxide electrodes and Pb(Zr,Ti)O3 (PZT) as ferroelectric layer, are investigated by the short-circuit photocurrent (SC-PHC) in the 200800nm wavelength domain. The band-gap dependence on the Zr content was determined from the spectral distribution of the SC-PHC signal. It was found that the band-gap value increases linearly with the Zr content, from about 3.9eV to about 4.4eV . It is shown that the sign and the magnitude of the signal depend on the internal bias and on the spontaneous polarization direction and value. The photocurrent describes a hysteresis loop similar to that of the ferroelectric polarization and can be used as a nondestructive readout of the nonvolatile memories based on PZT films. The existence of a significant SC-PHC signal at wavelengths corresponding to subgap energies is attributed to the presence of charged, deep levels in the forbidden band. It is also shown that the epitaxial PZT films have the potential for solid-state UV detectors, with current responsivity as high as 1mAW . The results are not entirely consistent with a bulk photovoltaic effect and are discussed in the frame of a Schottky barrier model for the metal-ferroelectric interface.
Published: 15 March 2007
Journal of Applied Physics, Volume 101; https://doi.org/10.1063/1.2436836

Abstract:
Mixed layers of copper-phthalocyanine ( p -conductive) and fullerene ( n -conductive) are used for the fabrication of organic field-effect transistors(OFET) and inverters. Regarding the electrical characteristics of these donor-acceptor blends they show ambipolar charge carrier transport, whereas devices made from only one of the materials show unipolar behavior. Such mixed films are model systems for ambipolar transport with adjustable field-effect mobilities for electrons and holes. By variation of the mixing ratio it is possible to balance the transport of both charge-carrier types. In this paper we discuss the variation of mobility and threshold voltage with the mixing ratio and demonstrate ambipolar inverters as a leadoff application. The gained results were analyzed by simulations using an analytical model for ambipolar transistors and subsequently compared to complementary inverters.
S. S. Sidhu, Leroy Heaton, D. D. Zauberis,
Published: 1 September 1956
Journal of Applied Physics, Volume 27, pp 1040-1042; https://doi.org/10.1063/1.1722538

Abstract:
Titanium and zirconium alloy system consists of a continuous series of random substitutional solid solutions of solvent and solute atoms. Titaniumscatters thermal neutrons in the opposite phase from those scattered by zirconium, the scattering amplitudes being: b Ti=−0.38×10−12 cm and b Zr=0.62×10−12 cm. An alloy containing 62 atomic percent titanium and 38 atomic percent zirconium is developed that gives no coherent scattering reflections in its neutron diffraction pattern, and is extremely useful in constructing devices in which scattering of thermal neutrons is not desired. Based on negative and positive scattering amplitudes of different isotopes of the same element for thermal neutrons, development of isotopic alloys is suggested.
S. I. Rubinow, T. T. Wu
Published: 1 September 1956
Journal of Applied Physics, Volume 27, pp 1032-1039; https://doi.org/10.1063/1.1722537

Abstract:
The total scattering cross section in the short wavelength limit is considered in this paper. The problems treated include diffraction of a plane electromagnetic wave by a conducting cylinder (two possible polarizations) or a conducting sphere, acoustic scattering by a rigid sphere, and quantum‐mechanical scattering by an impenetrable sphere. The first correction term to the geometric optics result is computed. In each case, this term is proportional to (ka)−2/3. The constant of proportionality depends on the specific geometry.
C. C. Cutler
Published: 1 September 1956
Journal of Applied Physics, Volume 27, pp 1028-1029; https://doi.org/10.1063/1.1722535

Abstract:
A thin strip or hollow electron beam drifting in a magnetic field directed parallel to the direction of motion is in an unstable condition. As a result of initial nonuniformities the beam breaks up into a series of ``spiral nebulae.'' This paper is written to describe some experimental observations which are of help in understanding the phenomenon, and to show that it can be applied to give useful amplification.
H. J. Juretschke, R. Landauer, J. A. Swanson
Published: 1 July 1956
Journal of Applied Physics, Volume 27, pp 838-839; https://doi.org/10.1063/1.1722496

A V Granato, Kurt Lucke
Published: 1 July 1956
Journal of Applied Physics, Volume 27, pp 789-805; https://doi.org/10.1063/1.1722485

Abstract:
A detailed discussion of data obtained over the past 15 years concerning the damping of mechanical vibrations in the kilocycle and megacycle range is given. The dependence of the decrement and modulus change on the variables of frequency and strain‐amplitude and many other parameters is compared with predictions of the dislocation theory developed in an earlier paper. Although general agreement is obtained, and many interesting quantitative results are found, it is not possible to say that the theory agrees everywhere since not all the necessary parameters are known well enough theoretically. A number of new experiments are suggested which may permit stronger conclusions to be made. This part may be read independently of the earlier paper by the reader who does not wish to follow the development of the theory in detail.
Joseph J. Loferski
Published: 1 July 1956
Journal of Applied Physics, Volume 27, pp 777-784; https://doi.org/10.1063/1.1722483

Abstract:
The theory of the photovoltaiceffect is used to predict the characteristics of a semiconductor which would operate with an optimum efficiency as a photovoltaicsolar energy converter. The existence of such an optimum material results from the interaction between the optical properties of the semiconductor which determine what fraction of the solar spectrum is utilized and its electrical properties which determine the maximum efficiency of conversion into electricity. Considerable attention is devoted to the effect of the forbidden energy gap (EG ) of the semiconductor. It is shown that atmospheric absorption causes a shift in the solar spectrum which changes the value of the optimum forbidden energy gap between the limits 1.2 ev
A V Granato, Kurt Lucke
Published: 1 June 1956
Journal of Applied Physics, Volume 27, pp 583-593; https://doi.org/10.1063/1.1722436

Abstract:
A quantitative theory of damping and modulus changes due to dislocations is developed. It is found that the model used by Koehler of a pinned dislocation loop oscillating under the influence of an applied stress leads to two kinds of loss, one frequency dependent and the other not. The frequency dependent loss is found to have a maximum in the high megacycle range. The second type of loss is a hysteresis loss which proves to be independent of frequency over a wide frequency range which includes the kilocycle range. This loss has a strain‐amplitude dependence of the type observed in the kilocycle range. The theory provides a quantitative interpretation of this loss.
Maurice A. Biot
Published: 1 March 1956
Journal of Applied Physics, Volume 27, pp 240-253; https://doi.org/10.1063/1.1722351

Abstract:
A unified treatment is presented of thermoelasticity by application and further developments of the methods of irreversible thermodynamics. The concept of generalized free energy introduced in a previous publication plays the role of a ``thermoelastic potential'' and is used along with a new definition of the dissipation function in terms of the time derivative of an entropy displacement. The general laws of thermoelasticity are formulated in a variational form along with a minimum entropy production principle. This leads to equations of the Lagrangian type, and the concept of thermal force is introduced by means of a virtual work definition. Heat conduction problems can then be formulated by the methods of matrix algebra and mechanics. This also leads to the very general property that the entropy density obeys a diffusion‐type law. General solutions of the equations of thermoelasticity are also given using the Papkovitch‐Boussinesq potentials. Examples are presented and it is shown how the generalized coordinate method may be used to calculate the thermoelastic internal damping of elastic bodies.
S. S. Brenner
Published: 1 December 1956
Journal of Applied Physics, Volume 27, pp 1484-1491; https://doi.org/10.1063/1.1722294

Abstract:
Tensile tests have been performed on whiskers of iron,copper, and silver 1.2 to 15 μ in diameter. The strongest whiskers which were less than 4 μ in diameter exhibited resolved elastic shear strengths of from two to six percent of their shear moduli. Stress‐strain determinations on iron have shown that large deviations from Hooke's law occur beyond two percent strain. As the whiskers increase in size, their strengths decrease with considerable scatter.
Leonard Liebermann
Published: 1 December 1956
Journal of Applied Physics, Volume 27, pp 1473-1476; https://doi.org/10.1063/1.1722292

Abstract:
Extremely low‐frequency (ELF) radio waves (10–500 cycles) originating in lightning were received over distances in excess of 15 000 km. Transmission conditions were equally good, day or night. Propagation distances were ascertained by analysis of higher frequency components (>1700 cycles) according to known methods. The receiving antenna employed an arrangement of grounded electrodes which uniquely determined the azimuthal direction of the source. Two distinct classes of ELF pulses are described which are attributed to different conditions of propagation.
B. M. Minton
Published: 1 October 1970
Journal of Mathematical Physics, Volume 11, pp 3061-3062; https://doi.org/10.1063/1.1665094

Abstract:
A new symmetry of the Racah coefficients is derived using a property of a generalized hypergeometric function of unit argument. The symmetry is similar in appearance, though not derivation, to that given by Regge.
Levere C. Hostler
Published: 1 October 1970
Journal of Mathematical Physics, Volume 11, pp 2966-2970; https://doi.org/10.1063/1.1665081

Abstract:
It is shown that the f‐dimensional nonrelativistic Coulomb Green's function and the associated reduced Green's functions can be obtained by differentiation of the corresponding functions in the 1‐dimensional (f odd) or 2‐dimensional (f even) case. A new expansion of the 3‐dimensional coordinate‐space Coulomb Green's function and a new sum formula for a product of two Laguerre polynomials with different arguments are derived.
G. Nienhuis
Published: 1 January 1970
Journal of Mathematical Physics, Volume 11, pp 239-243; https://doi.org/10.1063/1.1665053

Abstract:
The first‐order quantum corrections to the equations of state of an almost‐classical N‐particle system are calculated to all orders in the particle density by expanding the normalized Wigner distribution function in powers of h 2. In this way one avoids the expansion of the partition function, which has the unsatisfactory property that the correction terms diverge in the thermodynamic limit. Similarly, the first‐order quantum correction to the pair distribution function is derived.
G. Gallavotti, S. Miracle‐Sole
Published: 1 January 1970
Journal of Mathematical Physics, Volume 11, pp 147-154; https://doi.org/10.1063/1.1665040

Abstract:
We prove the impossibility of phase transitions for a class of infinite‐range potentials extending recent analogous results. We prove also a cluster property for the equilibrium state γ̄ and apply some collateral results to describe, in the case of finite‐range interactions, the state γ̄ in terms of a family of density distributions, and to verify a general variational property of γ̄ .
C. Itzykson
Journal of Mathematical Physics, Volume 10, pp 1109-1114; https://doi.org/10.1063/1.1664941

Abstract:
Given an irreducible unitary representation of a noncompact group, what happens if one tries to diagonalize one of the noncompact generators? We study some aspects of this question on an example, chosen to be a representation of the discrete series with j = −½ of the special real linear group in two dimensions.
P. C. Peters
Journal of Mathematical Physics, Volume 10, pp 1029-1031; https://doi.org/10.1063/1.1664930

Abstract:
The Brans‐Dicke gravitational scalar field is geometrized in the spirit of the Rainich‐Misner‐Wheeler geometrization of electromagnetism. Geometric equations are derived which imply that the Brans‐Dicke field is present and an explicit expression is given for this field in terms of geometrical quantities.
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