A β-Ta system for current induced magnetic switching in the absence of external magnetic field

Wenzhe Chen,Gang Xiao,Lijuan Qian

doi:10.1063/1.5008512

Abstract

Magnetic switching via Giant Spin Hall Effect (GSHE) has received great interest for its role in developing future spintronics logic or memory devices. In this work, a new material system (i.e. a transition metal sandwiched between two ferromagnetic layers) with interlayer exchange coupling is introduced to realize the deterministic field-free perpendicular magnetic switching. This system uses β-Ta, as the GSHE agent to generate a spin current and as the interlayer exchange coupling medium to generate an internal field. The critical switching current density at zero field is on the order of 106 A/cm2 due to the large spin Hall angle of β-Ta. The internal field, along with switching efficiency, depends strongly on the orthogonal magnetization states of two ferromagnetic coupling layers in this system.

Highlights

As a result of Giant Spin Hall Effect (GSHE), exerts a spin transfer torque to manipulate the magnetization direction, which provides the possibility of applications in logic and memory devices.[1,2,3,4]
Transition metals, such as Hf, Pt, β-Ta and β-W,1,3,5–11 possess large spin Hall angles (SHAs); in other words, they are highly efficient in generating a spin current from a charge current
Realizing zero-field deterministic perpendicular magnetic switching has recently been a popular topic in the spintronics research and development communities

Summary

INTRODUCTION

As a result of Giant Spin Hall Effect (GSHE), exerts a spin transfer torque to manipulate the magnetization direction, which provides the possibility of applications in logic and memory devices.[1,2,3,4] Transition metals, such as Hf, Pt, β-Ta and β-W,1,3,5–11 possess large spin Hall angles (SHAs); in other words, they are highly efficient in generating a spin current from a charge current. Others have attempted to replace the transition metals with the antiferromagnetic (AFM) materials to generate spin current and spin transfer torque.[13,14,15,16,17] With the help of AFM material, the internal exchange biasing field exerted on the adjacent perpendicular Ferromagnetic (FM) layer makes field-free magnetic switching possible. This kind of approach might lead to two issues: an incomplete field-free magnetic switching,[17] and a too-large critical switching current density due to the small SHAs of AFM materials.[18]. We study the samples with different β-Ta thickness and annealing conditions in order to understand the field-free switching mechanism better

SAMPLE PREPARATION AND CHARACTERIZATION

PULSE CURRENT INDUCED MAGNETIC SWITCHING

Findings

CONCLUSION