Universal domain wall dynamics under electric field in Ta/CoFeB/MgO devices with perpendicular anisotropy.

Weiwei Lin,Karin Garcia,Guillaume Agnus,Berthold Ocker,Dafiné Ravelosona,Weisheng Zhao,Nicolas Vernier,Eric E Fullerton

doi:10.1038/ncomms13532

Abstract

Electric field effects in ferromagnetic metal/dielectric structures provide a new route to control domain wall dynamics with low-power dissipation. However, electric field effects on domain wall velocities have only been observed so far in the creep regime where domain wall velocities are low due to strong interactions with pinning sites. Here we show gate voltage modulation of domain wall velocities ranging from the creep to the flow regime in Ta/Co40Fe40B20/MgO/TiO2 structures with perpendicular magnetic anisotropy. We demonstrate a universal description of the role of applied electric fields in the various pinning-dependent regimes by taking into account an effective magnetic field being linear with the electric field. In addition, the electric field effect is found to change sign in the Walker regime. Our results are consistent with voltage-induced modification of magnetic anisotropy. Our work opens new opportunities for the study and optimization of electric field effect at ferromagnetic metal/insulator interfaces.

Highlights

Electric field effects in ferromagnetic metal/dielectric structures provide a new route to control domain wall dynamics with low-power dissipation
To avoid any temperature rise, the experiments were performed under low leakage current below 20 nA, which corresponds to gate voltages ranging from À 1.5 to 1.5 V
In conclusion, beyond the important finding of the universal description of electric field-induced domain wall (DW) motion, the possibility to both obtain depining efficiency up to 2.5 mT V À 1 nm and control DW velocity up to the flow regime in CoFeB/MgO structures opens new perspectives for low power spintronic applications such as solid state memories and logic devices. We believe that these electric field effects can be used to lower the energy barrier for stored DWs, leading to a smaller spin-polarized currents to depin and move them

Summary

Introduction

Electric field effects in ferromagnetic metal/dielectric structures provide a new route to control domain wall dynamics with low-power dissipation. We show gate voltage modulation of domain wall velocities ranging from the creep to the flow regime in Ta/Co40Fe40B20/MgO/TiO2 structures with perpendicular magnetic anisotropy. PMA at the CoFeB/MgO interface can be manipulated efficiently through gate voltage control[15,16] These materials are considered as the most promising, for spin transfer torque magnetic random access memory[26,27] and for DW-based memories[28], as a combination of spin Hall effect and Dzyaloshinskii–Moriya interaction leads to efficient DW propagation under current[29,30,31]. The effect of gate voltage on DW velocity is found to be relatively large in the low-field regime, but it strongly decreases with increasing magnetic field. It is noteworthy that these results do not depend on the direction of magnetic fields (Supplementary Fig. 1) and were demonstrated in several devices with different width of ITO electrodes (Supplementary Fig. 2)

Methods

Results

Conclusion