Size and temperature dependence of M-H loop for Pt/CoFe/IrMn heterojunction

M-H loops of current-driven spin-orbit torque (SOT) devices with NM/FM/AFM structure have been simulated at different temperature from 50-400 K by Hybrid Monte-Carlo micromagnetics in nanodots and large-sized films. The model includes the polycrystalline microstructure. The effects of anisotropy defects size on M-H loops of dots are discussed, which coincide with experimental scaling tendency, where a lower Kmin at the defect center strongly influences the switching coercivity. Both the defect size and the temperature increase reduces the perpendicular coercivity Hc of nanodots. If the equivalent current-induced switching field is set as 100 mT, the critical switchable diameter of nanodots is around 50 nm with defect damage region of Kmin<0.65K, whereas in nearly perfectly deposited films (Kmin→K or insensitive to dot areas change), the critical switchable diameter will increase to around 100 nm [A. Kurenkov, Appl. Phys. Lett., 110, 9, (2017)].