Second-harmonic Signature of Chiral Spin Structures in W/Pt/Co Heterostructures with Tunable Magnetic Anisotropy
Authors: Wang, Yang; Chan, Ying-Ting; Wang, Xiao; Wang, Tao; Cheng, Xuemei M.; Wu, Weida; Xiao, John Q.
Source: Journal of Physics D-Applied Physics, Volume: 56, Issue: 20, Article Number: 205002, DOI: 10.1088/1361-6463/acc40f, 2023
Publication Type: Article
Abstract: Second-harmonic Hall voltage (SHV) measurement method has been widely used to characterize the strengths of spin–orbit torques (SOTs) in heavy metal/ferromagnet thin films saturated in the single-domain regime. Here, we show that the magnetic anisotropy of a W/Pt/Co trilayer can be robustly tuned from in-plane to out-of-plane by varying W, Pt, or Co thicknesses. Moreover, in samples with easy-cone anisotropy, SHV measurements exhibit anomalous ‘humps’ in the multidomain regime accessed by applying a nearly out-of-plane external magnetic field. These hump features can only be explained as a result of the formation of Néel-type domain walls, efficiently driven by nevertheless small SOTs in this double heavy metal heterostructure with canceling spin Hall angles.
Xuemei M. Cheng is dean of graduate studies and professor of physics.