Orbital torque in Ferromagnet/Nonmagnet/Oxide systems

Junyeon KIM

Utilization of the orbital angular momentum (OAM) opens a new way for an alternative method of the spin manipulation. Possibility of using wide range of materials, which comes from the fact that an electrical generation of the OAM does not require a large spin-orbit coupling, is the most remarkable virtue. In this talk, we introduce Ferromagnet (FM)/Nonmagnet (NM)/Al2O3 stacks as a highly efficient platform for current-induced torques and spin-orbitronic devices [1]. A striking feature we find is that the torque efficiency for the FM/Cu/Al2O3 system is highly affected by the annealing temperature and the choice of the FM. Moreover, we find that some samples exhibit gigantic torque efficiency of ~0.25, indicating that the OAM plays a significant role in current-induced torques. We also present our recent results on the variation of the torque efficiency for FM/Ru/Al2O3 [2] and various types of oxide materials in FM/Cu/oxide stacks [3]. Further discussion will be given during the workshop.

[1] J. Kim et al., Phys. Rev. B 103, L020407 (2021)
[2] L. Liao et al., Phys. Rev. B 105, 104434 (2022)
[3] J. Kim et al. in preparation