Perpendicular Magnetic Anisotropy and Interfacial Dzyaloshinskii-Moriya Interaction in Pt/CoFeSiB Structures

Abstract

Magnetic materials exhibiting perpendicular magnetic anisotropy (PMA) have an important role in the development of high-density magnetic random-access memory and domain-wall devices. Exotic physical phenomena result from spin-orbit coupling, such as PMA and the interfacial Dzyaloshinskii-Moriya interaction (iDMI), at interfaces between nonmagnetic (NM) and ferromagnetic (FM) materials. We report on the NM Pt thickness dependence of PMA and iDMI in Ta/Pt/CoFeSiB/Ta films and the MgO thickness dependence of PMA in Ta/Pt/CoFeSiB/MgO/Ta films. We selected amorphous FM CoFeSiB because of its lower saturation magnetization (560 emu/cm3) than that of Co or CoFeB, which may be beneficial for lowering the current density for switching. All samples were deposited by dc magnetron sputtering and annealed at 300 °C for 1 h. The Ta(3)/Pt(5)/CoFeSiB(1.5)/Ta(5) (nm) film exhibited PMA in the as-deposited state as well as after heat treatment. This structure possessed an iDMI energy density of 0.386 mJ/m2.