Communications Physics

Journal Information
EISSN : 2399-3650
Current Publisher: Springer Science and Business Media LLC (10.1038)
Former Publisher:
Total articles ≅ 611
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Anamul Md. Hoque, Dmitrii Khokhriakov, Klaus Zollner, Bing Zhao, Bogdan Karpiak, ,
Communications Physics, Volume 4, pp 1-9; doi:10.1038/s42005-021-00611-6

The ability to engineer new states of matter and control their spintronic properties by electric fields is at the heart of future information technology. Here, we report a gate-tunable spin-galvanic effect in van der Waals heterostructures of graphene with a semimetal of molybdenum ditelluride at room temperature due to an efficient spin-charge conversion process. Measurements in different device geometries with control over the spin orientations exhibit spin-switch and Hanle spin precession behavior, confirming the spin origin of the signal. The control experiments with the pristine graphene channels do not show any such signals. We explain the experimental spin-galvanic signals by theoretical calculations considering the spin-orbit induced spin-splitting in the bands of the graphene in the heterostructure. The calculations also reveal an unusual spin texture in graphene heterostructure with an anisotropic out-of-plane and in-plane spin polarization. These findings open opportunities to utilize graphene-based heterostructures for gate-controlled spintronic devices.
Karsten Jedamzik, Levon Pogosian,
Communications Physics, Volume 4, pp 1-6; doi:10.1038/s42005-021-00628-x

The mismatch between the locally measured expansion rate of the universe and the one inferred from the cosmic microwave background measurements by Planck in the context of the standard ΛCDM, known as the Hubble tension, has become one of the most pressing problems in cosmology. A large number of amendments to the ΛCDM model have been proposed in order to solve this tension. Many of them introduce new physics, such as early dark energy, modifications of the standard model neutrino sector, extra radiation, primordial magnetic fields or varying fundamental constants, with the aim of reducing the sound horizon at recombination r ⋆. We demonstrate here that any model which only reduces r ⋆ can never fully resolve the Hubble tension while remaining consistent with other cosmological datasets. We show explicitly that models which achieve a higher Hubble constant with lower values of matter density Ω m h 2 run into tension with the observations of baryon acoustic oscillations, while models with larger Ω m h 2 develop tension with galaxy weak lensing data.
Alejandro R.-P. Montblanch, Dhiren M. Kara, , Carola M. Purser, Matthew S. G. Feuer, , Lucio Stefan, Ying Qin, Mark Blei, Gang Wang, et al.
Communications Physics, Volume 4, pp 1-8; doi:10.1038/s42005-021-00625-0

Interlayer excitons in layered materials constitute a novel platform to study many-body phenomena arising from long-range interactions between quantum particles. Long-lived excitons are required to achieve high particle densities, to mediate thermalisation, and to allow for spatially and temporally correlated phases. Additionally, the ability to confine them in periodic arrays is key to building a solid-state analogue to atoms in optical lattices. Here, we demonstrate interlayer excitons with lifetime approaching 0.2 ms in a layered-material heterostructure made from WS2 and WSe2 monolayers. We show that interlayer excitons can be localised in an array using a nano-patterned substrate. These confined excitons exhibit microsecond-lifetime, enhanced emission rate, and optical selection rules inherited from the host material. The combination of a permanent dipole, deterministic spatial confinement and long lifetime places interlayer excitons in a regime that satisfies one of the requirements for simulating quantum Ising models in optically resolvable lattices.
Ruiqi Zhang, Christopher Lane, , Johannes Nokelainen, Bernardo Barbiellini, Robert S. Markiewicz, Arun Bansil,
Communications Physics, Volume 4, pp 1-12; doi:10.1038/s42005-021-00621-4

Recent discovery of superconductivity in the doped infinite-layer nickelates has renewed interest in understanding the nature of high-temperature superconductivity more generally. The low-energy electronic structure of the parent compound NdNiO2, the role of electronic correlations in driving superconductivity, and the possible relationship between the cuprates and the nickelates are still open questions. Here, by comparing LaNiO2 and NdNiO2 systematically within a parameter-free, all-electron first-principles density-functional theory framework, we reveal the role of Nd 4f electrons in shaping the ground state of pristine NdNiO2. Strong similarities are found between the electronic structures of LaNiO2 and NdNiO2, except for the effects of the 4f electrons. Hybridization between the Nd 4f and Ni 3d orbitals is shown to significantly modify the Fermi surfaces of various magnetic states. In contrast, the competition between the magnetically ordered phases depends mainly on the gaps in the Ni $$3{d}_{{x}^{2}-{y}^{2}}$$ 3 d x 2 − y 2 band. Our estimated value of the on-site Hubbard U in the nickelates is similar to that in the cuprates, but the value of the Hund’s coupling J H is found to be sensitive to the Nd magnetic moment. In contrast with the cuprates, NdNiO2 presents 3D magnetism with competing antiferromagnetic and (interlayer) ferromagnetic exchange, which may explain why the T c is lower in the nickelates.
Communications Physics, Volume 4, pp 1-13; doi:10.1038/s42005-021-00605-4

Simplicial complexes capture the underlying network topology and geometry of complex systems ranging from the brain to social networks. Here we show that algebraic topology is a fundamental tool to capture the higher-order dynamics of simplicial complexes. In particular we consider topological signals, i.e., dynamical signals defined on simplices of different dimension, here taken to be nodes and links for simplicity. We show that coupling between signals defined on nodes and links leads to explosive topological synchronization in which phases defined on nodes synchronize simultaneously to phases defined on links at a discontinuous phase transition. We study the model on real connectomes and on simplicial complexes and network models. Finally, we provide a comprehensive theoretical approach that captures this transition on fully connected networks and on random networks treated within the annealed approximation, establishing the conditions for observing a closed hysteresis loop in the large network limit.
Lu Zhong, Mamadou Diagne, Weiping Wang,
Communications Physics, Volume 4, pp 1-12; doi:10.1038/s42005-021-00620-5

Despite a number of successful approaches in predicting the spatiotemporal patterns of the novel coronavirus (COVID-19) pandemic and quantifying the effectiveness of non-pharmaceutical interventions starting from data about the initial outbreak location, we lack an intrinsic understanding as outbreak locations shift and evolve. Here, we fill this gap by developing a country distance approach to capture the pandemic’s propagation backbone tree from a complex airline network with multiple and evolving outbreak locations. We apply this approach, which is analogous to the effective resistance in series and parallel circuits, to examine countries’ closeness regarding disease spreading and evaluate the effectiveness of travel restrictions on delaying infections. In particular, we find that 63.2% of travel restrictions implemented as of 1 June 2020 are ineffective. The remaining percentage postponed the disease arrival time by 18.56 days per geographical area and resulted in a total reduction of 13,186,045 infected cases. Our approach enables us to design optimized and coordinated travel restrictions to extend the delay in arrival time and further reduce more infected cases while preserving air travel.
Bo Lv, Rui Chen, , Chunying Guan, Bin Zhou, Guohua Dong, Chao Zhao, Yicheng Li, Ying Wang, Huibin Tao, et al.
Communications Physics, Volume 4, pp 1-1; doi:10.1038/s42005-021-00642-z

, Alexandru Crivoi, Xiuyuan Peng, Lu Shen, Yunjiao Pu, , Steven A. Cummer
Communications Physics, Volume 4, pp 1-8; doi:10.1038/s42005-021-00617-0

Acoustic tweezers use ultrasound for contact-free manipulation of particles from millimeter to sub-micrometer scale. Particle trapping is usually associated with either radiation forces or acoustic streaming fields. Acoustic tweezers based on single-beam focused acoustic vortices have attracted considerable attention due to their selective trapping capability, but have proven difficult to use for three-dimensional (3D) trapping without a complex transducer array and significant constraints on the trapped particle properties. Here we demonstrate a 3D acoustic tweezer in fluids that uses a single transducer and combines the radiation force for trapping in two dimensions with the streaming force to provide levitation in the third dimension. The idea is demonstrated in both simulation and experiments operating at 500 kHz, and the achieved levitation force reaches three orders of magnitude larger than for previous 3D trapping. This hybrid acoustic tweezer that integrates acoustic streaming adds an additional twist to the approach and expands the range of particles that can be manipulated.
Shu-Ze Wang, Ming-Qiang Ren, Sha Han, Fang-Jun Cheng, Xu-Cun Ma, Qi-Kun Xue,
Communications Physics, Volume 4, pp 1-8; doi:10.1038/s42005-021-00619-y

Local quasiparticle states around impurities provide essential insight into the mechanism of unconventional superconductivity, especially when the candidate materials are proximate to an antiferromagnetic Mott-insulating phase. While such states have been reported in atom-based cuprates and iron-based compounds, they are unexplored in organic superconductors which feature tunable molecular orientation. Here we employ scanning tunneling microscopy and spectroscopy to reveal multiple forms of robustness of an exotic s-wave superconductivity in epitaxial Rb3C60 films against merohedral disorder, non-magnetic single impurities and step edges at the atomic scale. Yu-Shiba-Rusinov (YSR) states, induced by deliberately incurred Fe adatoms that act as magnetic scatterers, have also been observed. The YSR bound states show abrupt spatial decay and vary in energy with the Fe adatom registry. These results and a doping-dependent study of superconductivity point towards local electron pairing in which the multiorbital electronic correlations and intramolecular phonons together drive the high-temperature superconductivity of doped fullerenes.
Junya Ikeda, , , Takeshi Seki, Kentaro Nomura, Koki Takanashi,
Communications Physics, Volume 4, pp 1-6; doi:10.1038/s42005-021-00627-y

Two-dimensional (2D) surface of the topological materials is an attractive channel for the electrical conduction reflecting the linearly-dispersive electronic bands. Thickness-dependent sheet conductance measurement is a reliable method to evaluate the 2D and three-dimensional (3D) electrical conducting channel separately but has rarely been applied for Weyl semimetals. By applying this method to thin films of a Weyl semimetal Co3Sn2S2, here we show that the 2D conducting channel clearly emerges under the ferromagnetic phase, indicating a formation of the Fermi arcs projected from Weyl nodes. Comparison between 3D conductivity and 2D conductance provides the effective thickness of the surface conducting region being estimated to be approximately 20 nm, which would reflect the Weyl feature of electronic bands of the Co3Sn2S2. The emergent surface conduction will provide a pathway to activate quantum and spintronic transport features stemming from a Weyl node in thin-film-based devices.
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