Orbital magnetization and its effects in spin-chiral ferromagnetic kagomé lattice

Abstract

Recently, Berry phase in the semiclassical dynamics of Bloch electrons has been found to make a correction to the phase-space density of states and a general multiband formula for finite-temperature orbital magnetization has been given [D. Xiao et al., Phys. Rev. Lett. 97, 026603 (2006)], where the orbital magnetization $\mathcal{M}$ consists of two parts, i.e., the conventional part ${M}_{c}$ and the Berry-phase correction part ${M}_{\ensuremath{\Omega}}$. Using this general formula, we theoretically investigate the orbital magnetization and its effects on thermoelectric transport and magnetic susceptibility properties of the two-dimensional kagom\'e lattice with spin anisotropies included. The study in this paper is highly interesting because of the nonzero spin chirality parameter $\ensuremath{\phi}$ (see text), which results in profound effects on the topology of the electron Bloch states and the orbital magnetization properties. It is found that the two parts in orbital magnetization oppose each other. In particular, we show that the orbital magnetization displays fully different behaviors in the metallic and insulating regions, which is due to the different roles ${M}_{c}$ and ${M}_{\ensuremath{\Omega}}$ play in these two regions. The anomalous Nernst conductivity is also calculated, which displays a peak-valley structure as a function of the electron Fermi energy.