Finite temperature spin-dynamics and phase transitions in spin-orbital models
Abstract
We study finite temperature properties of a generic spin-orbital model relevant to transition metal compounds, having coupled quantum Heisenberg-spin and Ising-orbital degrees of freedom. The model system undergoes a phase transition, consistent with that of a 2D Ising model, to an orbitally ordered state at a temperature set by short-range magnetic order. At low temperatures the orbital degrees of freedom freeze-out and the model maps on to a quantum Heisenberg model. The onset of orbital excitations causes a rapid scrambling of the spin spectral weight away from coherent spin-waves, which leads to a sharp increase in uniform magnetic susceptibility just below the phase transition, reminiscent of the observed behavior in the Fe-pnictide materials.
Cite
@article{arxiv.0908.0800,
title = {Finite temperature spin-dynamics and phase transitions in spin-orbital models},
author = {C. -C. Chen and B. Moritz and J. van den Brink and T. P. Devereaux and R. R. P. Singh},
journal= {arXiv preprint arXiv:0908.0800},
year = {2009}
}
Comments
4 pages