Fig. 7: Comparison with other HMs.
From: Optical spin-orbit torque in heavy metal-ferromagnet heterostructures
The helicity-dependent Kerr rotation, difference between RCP and LCP, (ΔθR-L) of a the sap/HM(5)/Co(3)/MgO(3) and b the sap/HM(5)/Cu(2)/Co(3)/MgO(3) samples, where HM is Ta (black squares), W (red circles), Pd (blue up-triangles), and Pt (olive down-triangles) at a photon’s energy of 1.58 eV. The y-axis of b is the same as that of a. c The quantum efficiency (η) of the sap/HM(5)/Co(3)/MgO(3) (black squares), sap/HM(5)/Cu(2)/Co(3)/MgO(3) (red circles) samples. The η is calculated from dynamics Kerr rotation of a and b, static Kerr rotation (Supplementary Note 6), and light absorption (Supplementary Note 5). The vertical dashed lines indicate the work functions Ta, W, Co, Pd, and Pt at the (111) surface32.
