Spin-orbitronics utilizes electrically induced spin currents and spin polarization caused by the spin Hall effect (SHE) and spin Rashba-Edelstein effect (SREE). Recent first-principles calculations have however predicted that there should exist much larger orbital currents and induced orbital polarizations, due to the orbital Hall effect (OHE) and orbital Rashba-Edelstein effect (OREE). This provides a new perspective for future utilization of orbital angular momentum, instead of spin, as information carrier in the emerging field orbitronics.
I will discuss our recent first-principles linear-response theory calculations for the electrically induced spin and orbital polarization in symmetry-broken antiferromagnets CuMnAs and Mn2Au where we find that the OREE is much larger than the SREE. We further show that both the OHE and OREE do not require spin-orbit interaction (SOI) and large effects can be obtained for materials containing light atoms. In addition, we show that for bulk 3d ferromagnets as well as in Pt/3d-metal bilayers there exists a magnetic spin Hall effect (MSHE) and a magnetic orbital Hall effect (MOHE) that are time-reversal odd in contrast to the time-reversal even SHE and OHE. We also predict values for the thermal counterparts, namely, the spin Nernst effect, and for the as-yet unobserved orbital Nernst effect and their magnetic counterparts.
While theory has predicted various large orbital effects, their experimental observation has been challenging. I will discuss recent investigations that definitely confirm the existence of sizable current-induced orbital accumulation.