Effects of spin fluctuations and anomalous thermal expansion of
- 2 June 2010
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 81 (21)
- https://doi.org/10.1103/physrevb.81.214402
Abstract
We suggest a model for the magnetic dynamics of plutonium and its alloys in order to show that the dynamical fluctuations of the magnetization density, or spin fluctuations, may be responsible for the anomalies of their observed thermal expansion. We show that due to strong magnetoelastic coupling, spin fluctuations may essentially contribute to the volume strain by giving a negative magnetovolume contribution that is proportional to the squared local magnetic moment and the magnetic Gruneisen constant which is negative in plutonium. In the presented model, the local magnetic moment increases as the temperature rises, resulting in the interplay between the positive contributions to the volume strain from the lattice and the negative contribution from spin fluctuations, and finally leads to the Invar anomaly or to the negative coefficient of thermal expansion. Our results agree closely with the measured thermal-expansion data for Pu-Ga alloys. DOI: http://dx.doi.org/10.1103/PhysRevB.81.214402 © 2010 The American Physical Society
Keywords
This publication has 20 references indexed in Scilit:
- First-principles elastic properties ofPhysical Review B, 2009
- Magnetic state and electronic structure of plutonium from “first principles” calculationsJournal of Alloys and Compounds, 2007
- Self-interaction-corrected local spin density theory ofelectron localization in actinidesPhysical Review B, 2007
- Dynamical mean-field theory investigation of specific heat and electronic structure of- and-plutoniumPhysical Review B, 2007
- Nature of non-magnetic strongly-correlated state in δ-plutoniumEurophysics Letters, 2006
- Absence of magnetic moments in plutoniumPhysical Review B, 2005
- Monte Carlo simulations of the stability of -PuJournal of Physics: Condensed Matter, 2003
- Density-functional investigation of magnetism in-PuPhysical Review B, 2002
- Zero-point spin fluctuations and the magnetovolume effect in itinerant-electron magnetismPhysical Review B, 1995
- Spin-polarized relativistic linear-muffin-tin-orbital method: Volume-dependent electronic structure and magnetic moment of plutoniumPhysical Review B, 1991