Spin Hall effect in Sr2RuO4 and transition metals (Nb,Ta)

Abstract

We study the intrinsic spin Hall conductivity (SHC) and the d-orbital Hall conductivity (OHC) in metallic d-electron systems based on the multiorbital tight-binding model. The obtained Hall conductivities are much larger than that in p-type semiconductors. The origin of these huge Hall effects is the "effective Aharonov-Bohm phase" induced by the signs of inter-orbital hopping integrals as well as atomic spin-orbit interaction. Huge SHC and OHC due to this mecahnism is ubiquitous in multiorbital transition metals.

Anomalous transport phenomena in Fermi liquids with strong magnetic fluctuations

“…Recently, we proposed a new mechanism for the giant SHE originating from the d-orbital degrees of freedom, which is absent in semiconductors [288,289,291]. In a multiorbital system, a conduction electron acquires the 'effective Aharonov-Bohm phase factor' due to d-atomic angular momentum, as explained in figure 40.…”

“…In a multiorbital system, a conduction electron acquires the 'effective Aharonov-Bohm phase factor' due to d-atomic angular momentum, as explained in figure 40. We studied the SHEs in Sr 2 RuO 4 [288], which is the first theoretical study of the SHE in d-electron systems, in Pt [289] and in various 4d and 5d transition metals [291]. It is found that the explanation in figure 40 seems to capture the characteristics of SHE in d-electron systems.…”

Effect of nonequilibrium order parameter on the optical response of superconductor Sr2RuO4

“…The Fermi energy of the layered perovskite oxide Sr 2 RuO 4 contains two the Ruthenium one-dimensional orbitals d xz and d yz and one two-dimensional orbital d xy [25][26][27][28]. The four-fold rotational crystal symmetry of this material causes that the d xz and d yz orbitals behave as a doublet whereas the d xy orbital to be a independent one.…”