First-principles calculations of orbital Hall and Nernst effects in monoatomic crystal to binary alloys and multilayers

Orbital Hall effect has attracted attention as a new degree of freedom in solid state in addition to the spin Hall effect [1,2]. Generation and controlling of orbital current offer highly-efficient magnetization switching in spin applications. In this work, intrinsic orbital Hall conductivity (OHC) and orbital Nernst conductivity (ONC), thermally-driven transport, in monoatomic crystal are investigated using first-principles full-potential linearized augmented plane wave method [3]. The systematic calculations of chemical trend (atomic element) for 40 elements in the periodic table clarified that the OHC is maximized near the middle of transition metals (TMs) with d electrons, which agrees with the earlier work [4]. For these d TMs, the OHC shows large value in wide energy region within the rigid band analysis, indicating the significant contribution of Berry curvature in not only localized d states but also itinerant p states. On the other hand, the ONC accompanies localized d states, especially near the d band edges in the density of states, and a large ONC is obtained in Ni (assumed to be nonmagnetic). We also discuss the results for binary alloys and multilayers in terms of atomic composition dependence and stacking effect.