Giant Piezomagnetism and Noncollinear Spin Current from C-Paired Spin Valley Locking

Junwei Liu, The Hong Kong University of Science and Technology

January 28, 2022

In this talk, I will take our recently proposed new type of spin-valley locking (SVL), named C-paired SVL, in antiferromagnetic systems. It directly connects the spin/valley space with the real space, and hence enables both static and dynamical controls of spin and valley to realize a multifunctional antiferromagnetic material. The new emergent quantum degree of freedom in the C-paired SVL is comprised of spin-polarized valleys related by a crystal symmetry instead of the time-reversal symmetry. Thus, both spin and valley can be accessed by simply breaking the corresponding crystal symmetry. Typically, one can use a strain field to induce a large net valley polarization/magnetization and use a charge current to generate a large noncollinear spin current. We predict the realization of the C-paired SVL in monolayer V2Se2O, which indeed exhibits giant piezomagnetism and can generate a large transverse spin current. Based on symmetry analysis and first-principles calculations, we also found C-paired SVL can exist in the following experimentally verified AFM materials, NaOsO3, LaMnO3, LaCrO3, TbFeO3, MnTe, RuO2, MnF2, FeF2, CoF2, and NiF2. Our findings provide new opportunities to integrate various controls of spin and valley with nonvolatile information storage in a single material, which is highly desirable for versatile fundamental research and device applications.

[1] Hai-Yang Ma, Mengli Hu, Nana Li, Jianpeng Liu, Wang Yao, Jin-Feng Jia, Junwei Liu, Multifunctional antiferromagnetic materials with giant piezomagnetism and noncollinear spin current, Nature Communications, 12, 2846 (2021)