Chirality-dependent spin polarization in metals: linear and quadratic responses
Kosuke Yoshimi, Yusuke Kato, Yuta Suzuki, Shuntaro Sumita, Takuro Sato, Hiroshi M. Yamamoto, Yoshihiko Togawa, Hiroaki Kusunose, Jun-ichiro Kishine
Published: 2024/8/8
Abstract
We study spin polarization induced by locally injected electric currents in a metal whose spin--orbit interaction reflects its structural chirality. We reveal both spin polarization in bulk in the linear response and antiparallel spin polarization near the boundary in the quadratic response against electric fields, and reproduce the experimentally observed correlation between the chirality of the metal and the direction of spin polarization. In particular, we elucidate that the sign of the quadratic spin accumulation is opposite to that expected from the bulk spin current. This sign discrepancy originates from the dipole-like charge distribution appearing in the quadratic response. Our method is applicable to a wide range of real materials with various types of spin--orbit coupling.