Abstract | Nonlinear response properties of solids have attracted tremendous interest recently. So far, the studies of nonlinear responses are mostly focused on the charge current, whereas the importance of nonlinear response of spin, another basic degree of freedom in solids, has not been widely appreciated. In this talk I will introduce our recent works on the 2nd order nonlinear electrical spin generation effect. This effect lifts the stringent requirement of linear spin-orbit torque for inversion breaking and heterostructures, enabling self-generated nonlinear spin-orbit torques in centrosymmetric ferromagnets [1,2] and antiferromagnets [3]. Such direct electrical manipulation of centrosymmetric magnets largely extends the material platform of magnetic memory devices, and pave the way for the emerging field of nonlinear spin-orbitronics. In the theoretical part, I will also discuss the definition of intrinsic nonlinear response. References: [1]C. Xiao, H. Liu*, W. Wu*, H. Wang, Q. Niu, and S. A. Yang, Intrinsic Nonlinear Electric Spin Generation in Centrosymmetric Magnets, Phys. Rev. Lett. 129, 086602 (2022). [2] C. Xiao*, W. Wu, H. Wang, Y.-X. Huang, X. Feng, H. Liu*, G.-Y. Guo*, Q. Niu, and S. A. Yang, Time-Reversal-Even Nonlinear Current Induced Spin Polarization, Phys. Rev. Lett. 130, 166302 (2023). [3] J. Cao, W. Wu, H. Liu*, S. Lai, C. Xiao*, X. C. Xie, and S. A. Yang, Nonlinear Neel Spin-Orbit Torque in Centrosymmetric Antiferromagnets, to appear on arXiv. |
