Fig. 2: Asymmetric field-driven switching of magnetization.
From: Spin-orbit torque switching of chiral magnetization across a synthetic antiferromagnet
a Hall resistance RH versus perpendicular magnetic field Hz for the synthetic antiferromagnet (SAF). The anomalous Hall part of RH that is proportional to the perpendicular magnetization Mz is dominant in the interpretation. Red arrows in the inset show the schematic of magnetic configurations at different stages during the Hall resistance measurement. The top and bottom red arrows represent magnetizations of the top and bottom ferromagnetic layers, respectively. b The schematic Hall bar structure with the definition of ϕH that is the relative angle between the in-plane field HIP and the x axis. c Asymmetric hysteresis loops measured when applying an in-plane magnetic field HIP = 100 Oe along ϕH = 90° (black) and ϕH = 270° (red). Dash-dotted lines indicate positions for negative (Hc1) and positive (Hc2) switching fields for HIP∥ϕH = 90°. Dashed lines indicate positions of field biases for HIP∥ϕH = 90° (black) and HIP∥ϕH = 270° (red). d ϕH dependence of the field bias HB. Open dots are experimental data and the line is fitted by a cosine function AB cos (ϕH − ϕAS) + BB where AB is the amplitude, ϕAS the angle for the asymmetric axis that is represented by the dashed line, BB the offset of the field bias. The insert shows the spatial distributions of ΔRH which reflects the in-plane asymmetry of interlayer exchange coupling (IEC) along the y axis. e Numerical calculations of asymmetric hysteresis loops for Mz when applying HIP = 100 Oe along ϕH = 90° (black) and ϕH = 270° (red). The interlayer Dzyaloshinskii–Moriya interaction (DMI) vector DInt along the −x axis with the amplitude of DInt = −0.1AInt was adopted in calculations. The insert is the schematic of magnetic configurations for different spin states at zero perpendicular field and at the in-plane field of HIP∥ϕH = 90° and HIP∥ϕH = 270°, respectively. f ϕH dependence of the field bias HB derived from the numerical calculation. Open dots are numerical calculation results and the line is fitted by a cosine function AB cos (ϕH − ϕAS). Arrows represent switching directions.
