Nomura Yusuke, Sakai Shiro, Arita Ryotaro
RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Phys Rev Lett. 2022 May 20;128(20):206401. doi: 10.1103/PhysRevLett.128.206401.
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_{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_{C}.
利用动力学平均场理论的团簇扩展，我们表明，受洪德物理影响的强关联金属在磁转变温度以上表现出显著的电子结构调制。特别是，在由于洪德耦合而具有大的局域磁矩的铁磁体（洪德铁磁体）中，即使在居里温度（(T_{C})）以上，费米面也会膨胀，就好像发生了自旋极化一样。在这种现象背后，有效的“洪德物理”在动量空间中起作用，源于强耦合 regime 中的铁磁涨落。由此产生的显著依赖于动量（空间非局域）的电子关联导致了涉及费米面体积变化和动量空间占据重新分布的电子结构重构。我们的发现将为深入理解(T_{C})以上洪德铁磁体的物理性质提供更深层次的见解。
