Fermi surface expansion above critical temperature in a Hund ferromagnet

Yusuke Nomura; Shiro Sakai; Ryotaro Arita

doi:10.1103/physrevlett.128.206401

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arXiv · 2110.04288

Fermi surface expansion above critical temperature in a Hund ferromagnet

Yusuke Nomura·Shiro Sakai·Ryotaro Arita

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Abstract

Using a cluster extension of the dynamical mean-field 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 ($T_{\rm C}$) as if a spin polarization occurred. Behind this phenomenon, effective ``Hund's physics'' works in momentum space, originating from ferromagnetic fluctuations in the strong coupling regime. The resulting significantly momentum-dependent (spatially nonlocal) electron correlations induce an electronic structure reconstruction involving a Fermi-surface volume change and a redistribution of the momentum-space occupation. Our finding will give a deeper insight into the physics of Hund's ferromagnets above $T_{\rm C}$.

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Yusuke Nomura, Shiro Sakai, Ryotaro Arita. 2021-10-08. Fermi surface expansion above critical temperature in a Hund ferromagnet. https://doi.org/10.1103/physrevlett.128.206401

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