The purpose of my research is studying spin-orbit coupling effects in magnetic multilayers. The advantage of spin-orbit coupling is that direct coupling between the spin angular momentum and the orbital motion allows for angular momentum flow from the lattice to electron spins. This allows manipulating and detecting magnetic states by applying an electrical current with high efficiency. Spin-orbit torque, which is a torque on magnetization induced by spin-orbit coupling, is a good example. Furthermore, other spin-related phenomena, such as spin motive force, magnetic damping, and magnetoresistance, are also significantly affected by spin-orbit coupling.
In magnetic multilayers, inversion symmetry is naturally broken, allowing new physics which have been protected by symmetry. The effects of symmetry breaking becomes more important when the dimension of the system goes down to nanoscale. Since the effective spin-orbit coupling parameter is magnified in the presence of symmetry breaking, the strong spin-orbit coupling effects not only give rise to quantitative corrections to known phenomena, but also result in qualitatively different behaviors.
Not only does spin-orbit copuling affect the magnetization dynamics in nonequilibrium situations, it also affects the equilibrium properties. Examples include the emergence of Dzyaloshinskii-Moriya interaction, perpendicular magnetic anisotropy, and skyrmion states. It means that the equilibrium properties are highly correlated with the nonequilibrium properties via the spin-orbit coupling parameter. Revealing such correlations would be not only deepen our understanding of spin-orbit coupling in magnetic nanostructures, but also advance the realization of spintronic device applications.
- Magnetization dynamics
- Spin-transfer torque and spin motive force
- Magnetic damping and anisotropy
- Motion of magnetic solitons
- Spin-orbit interaction in nanostructures
- Spin-orbit coupling effects in magnetic bilayers
- Interfacial spin-orbit coupling due to broken inversion symmetry
- Spin-orbit torque
- "Field-free switching of perpendicular magnetization through spin-orbit torque in antiferromagnet/ferromagnet/oxide structures", Y.-W. Oh, S.-h. C. Baek, Y. M. Kim, H. Y. Lee, K.-D. Lee, C.-G. Yang, E.-S. Park, Ki-S. Lee, K.-W. Kim, G. Go, J.-R. Jeong, B.-C. Min, H.-W. Lee, K.-J. Lee, and B.-G. Park, Nature Nanotechnology 11, 878-884 (2016).
- "Chirality from interfacial spin-orbit coupling effects in magnetic bilayers", K.-W. Kim, H.-W. Lee, K.-J. Lee, and M. D. Stiles, Physical Review Letters 111, 216601 (2013).
- "Current-induced motion of a transverse magnetic domain wall in the presence of spin Hall effect", S.-M. Seo (equal), K.-W. Kim (equal), J. Ryu, H.-W. Lee, and K.-J. Lee, Applied Physics Letters 101, 022405 (2012).
- "Prediction of giant spin motive force due to Rashba spin-orbit coupling", K.-W. Kim, J.-H. Moon, K.-J. Lee, and H.-W. Lee, Physical Review Letters 108, 217202 (2012).
- "Magnetization dynamics induced by in-plane currents in ultrathin magnetic nanostructures with Rashba spin-orbit coupling", K.-W. Kim, S.-M. Seo, J. Ryu, K.-J. Lee, and H.-W. Lee, Physical Review B 85, 180404(R) (2012).