Fermi surface expansion above critical temperature in a Hund ferromagnet
Abstract
Using a cluster extension of the dynamical meanfield theory, we show that strongly correlated metals subject to Hund's physics exhibit significant electronic structure modulations above magnetic transition temperatures. In particular, in a ferromagnet having a large local moment due to Hund's coupling (Hund's ferromagnet), the Fermi surface expands even above the Curie temperature ($T_c$) as if the spin polarization occurred. Behind this phenomenon, effective ``Hund's physics'' works in momentum space, originating from a ferromagnetic fluctuation in the strong coupling regime. The resulting significantly momentumdependent (spatially nonlocal) electron correlations induce an electronic structure reconstruction involving the Fermisurface volume change and the redistribution of the momentumspace occupation. Our finding will give a deeper insight into the physics of Hund's ferromagnets above $T_c$.
 Publication:

arXiv eprints
 Pub Date:
 October 2021
 arXiv:
 arXiv:2110.04288
 Bibcode:
 2021arXiv211004288N
 Keywords:

 Condensed Matter  Strongly Correlated Electrons;
 Condensed Matter  Superconductivity
 EPrint:
 Main text: 6 pages, 4 figures. Supplemental Materials: 3 pages, 8 figures