Spin-orbit torque and Nernst effect in Bi-Sb/Co heterostructures

Author(s): Roschewsky, Niklas; Walker, Emily S; Gowtham, Praveen; Muschinske, Sarah; Hellman, Frances; Bank, Seth R; Salahuddin, Sayeef | Abstract: © 2019 American Physical Society. Harmonic measurements of the longitudinal and transverse voltages in Bi-Sb/Co bilayers are presented. A large second harmonic voltage signal due to the ordinary Nernst effect is observed. In experiments where a magnetic field is rotated in the film plane, the ordinary Nernst effect shows the same angular dependence in the transverse voltage as the dampinglike spin-orbit torque and in the longitudinal voltage as the unidirectional spin-Hall magnetoresistance, respectively. Therefore, the ordinary Nernst effect can be a spurious signal in spin-orbit torque measurements, leading to an overestimation of the spin-Hall angle and spin-Hall conductivity in topological insulators or semimetals.