Spin-orbit torque induced magnetization anisotropy modulation in Pt/(Co/Ni)4/Co/IrMn heterostructure

Abstract

In this work, we show that domain wall (DW) dynamics within a system provide an alternative platform to characterizing spin-orbit torque (SOT) effective fields. In perpendicularly magnetized wires with a Pt/(Co/Ni) 4 /Co/IrMn stack structure, differential Kerr imaging shows that the magnetization switching process is via the nucleation of the embryo state followed by domain wall propagation. By probing the current induced DW motion in the presence of in-plane field, the SOT effective fields are obtained using the harmonic Hall voltage scheme. The effective anisotropy field of the structure decreases by 12% due to the SOT effective fields, as the in-plane current in the wire is increased.

Quantitative characterization of spin-orbit torques in Pt/Co/Pt/Co/Ta/BTO heterostructures due to the magnetization azimuthal angle dependence

“…In Fig. 8 This decrease might be related to the increase in SOT effective fields with increasing current density in the wire [30].…”

“…However, the ratio between dampinglike and fieldlike torques has been detected to vary between ~1 [30] and up to ~8 [31], which shows a rather complicated behavior. Ta-thickness dependence study using harmonic Hall measurement technique in Ta/CoFeB/MgO structure with perpendicular magnetic anisotropy (PMA) suggests a sign change of the fieldlike torque at small thicknesses of Ta (<1.5 nm) which is also nontrivial [32].…”

Efficient in-line skyrmion injection method for synthetic antiferromagnetic systems

“…SOTs have been the subject of many recent research endeavors due to their potential for efficient magnetization switching [18][19][20][21][22]. In particular, the spin accumulation at the heavy metal-ferromagnet interface due to the spin Hall effect has been found to be useful for magnetization switching.…”

Current-induced spin-orbit torque effective fields in multilayer structures with perpendicular magnetic anisotropy

“…Fan et al [48] managed to identify the contributions of the Rashba effect from interface effects by inserting a copper layer at the interface to minimize the Rashba effect and distinguish effects from Rashba and from SHE in Pt/CoFeB bilayers. However, the ratio between dampinglike and fieldlike torques has been detected to vary between ∼ 1 [43] and up to ∼ 8 [28], which shows a rather complicated behavior. Ta-thickness dependence study using harmonic Hall measurement technique in Ta/CoFeB/MgO structure with PMA suggests a sign change of the fieldlike torque at small thicknesses of Ta (<1.5 nm) which is also nontrivial [76].…”

“…Anisotropy and coercivity field are also found to decrease with increasing current density in the wire which is attributed to SOT effective fields. This chapter has been reproduced from published work in Journal of Applied Physics with the permission of AIP Publishing [43].…”