Progress of electrical control magnetization reversal and domain wall motion

Abstract

Electrical control of spins in magnetic materials and devices is one of the most important research topics in spintronics. We briefly describe the recent progress of electrical manipulations of magnetization reversal and domain wall motion.This review consists of three parts:basic concepts,magnetization manipulation by electrical current and voltage methods,and the future prospects of the field.The basic concepts,including the generation of the spin current,the interaction between the spin current and localized magnetization,and the magnetic dynamic Landau-Lifshitz-Gilbert-Slonczewski equation are introduced first.In the second part,we reviewed the progress of the magnetization controlled by electrical current and voltage. Firstly we review the electrical current control of the magnetization and domain wall motion.Three widely used structures, single-layer magnets,ferromagnet/heavy metal and ferromagnet/nonmagnetic metal/ferromagnet,are reviewed when current is used to induce magnetization reversal or drive domain wall motion.In a single-layer magnetic material structure,domain wall can be effectively driven by electrical current through spin transfer torque.The factors influencing the domain wall trapping and motion are also discussed.The electrical current control of the skyrmions has big potential applications due to much lower current density.Using the Dresselhaus and Rashba spin orbital coupling,the electrical current can also directly reverse the magnetization of single magnetic or antiferromagnetic layer.Then,we review the electrical current switching the magnetization of the ferromagnetic layer in ferromagnetic/heavy metal structures,where both spin Hall effect and Rashba effect can contribute to the current switching magnetization in such device structures. To identify the relative contributions of these two mechanisms,several quantitative studies are carried,concluding that spin Hall effect plays a major role,which is summarized in this review.Finally,we review the current switching magnetization of free layers in spin valve and magnetic tunnel junctions (MTJs) by spin transfer torque.We also discuss the approaches to the decrease of the critical current density in MTJs,which is desired for future applications.Alternatively,the electric field can also be used to manipulate the magnetization,where three methods are reviewed. Applying an electric field to the ferromagnetic/piezoelectric heterostructures,which changes the crystal structure of magnetic film through piezoelectric effects,realizes the change of the magnetic anisotropy of the ferromagnetic layer.In ferromagnetic/ferroelectric heterostructures,electric field changes the spin distribution and orbital hybridization at the surface of magnetic film through the magnet-electric coupling effects,and then controls the magnetization of the ferromagnetic layer.In ferromagnetic metal (semiconductor)/dielectric/metal structure,electric field controls the electron accumulation or depletion at the surface of the ferromagnetic metal or semiconductor,the change of the electron density in the magnetic layer in turn affects the magnetic exchange interaction and magnetic anisotropy.Finally,we present the prospects for the development of electrical control magnetization reversal and domain wall motion for future applications.