Electric-field control of ferromagnetism through oxygen ion gating

Hao-Bo Li,Yujia Wang,Zhuolu Li,Jing Ma,Pu Yu,Tianzhe Chen,Yujun Shi,Deqiang Feng,Qinghua Zhang,Weichao Wang,Zheng Duan,Kui Jin,Wei-Hua Wang,Cewen Nan,Nianpeng Lu,Shuzhen Yang,Hui Liu,Lin Gu

doi:10.1038/s41467-017-02359-6

Abstract

Electric-field-driven oxygen ion evolution in the metal/oxide heterostructures emerges as an effective approach to achieve the electric-field control of ferromagnetism. However, the involved redox reaction of the metal layer typically requires extended operation time and elevated temperature condition, which greatly hinders its practical applications. Here, we achieve reversible sub-millisecond and room-temperature electric-field control of ferromagnetism in the Co layer of a Co/SrCoO2.5 system accompanied by bipolar resistance switching. In contrast to the previously reported redox reaction scenario, the oxygen ion evolution occurs only within the SrCoO2.5 layer, which serves as an oxygen ion gating layer, leading to modulation of the interfacial oxygen stoichiometry and magnetic state. This work identifies a simple and effective pathway to realize the electric-field control of ferromagnetism at room temperature, and may lead to applications that take advantage of both the resistance switching and magnetoelectric coupling.

Highlights

Researchers have demonstrated that oxygen ions in oxide materials can be utilized to effectively manipulate the magnetic properties of ferromagnetic metal layers in metal/oxide heterostructures[10,11,12,13], through the electric-field control of reversible redox reactions within the metal layers
We note that for sputtered Co thin films with a granular nature as studied here, the magnetic switching field HS(j) can be divided into three interactions: Hsð jÞ 1⁄4 hsj þ hej xðmiÞ þ hmj sðmiÞ, which are the single grain switching long-range fimeladgn(ehtsjo)s, taitnitcerc-ogurapnliunlgar(himjnstðemraicÞt)i,onres(pheejcxtðimveilÞy)2,4.anAds illustrated in Fig. 4a, the inter-granular and long-range magnetic couplings lead to a rectangular shape hysteresis loop, while the intrinsic single grain magnetic switching results in a decay of the squareness
(Fig. 2b), the decay of squareness in the highresistance state (HRS) suggests that the interactions between the granular are reduced, because the oxygen ion adsorption on the Co granular surface suppresses the inter-granular couplings (Fig. 4b)[25]

Summary

Introduction

Researchers have demonstrated that oxygen ions in oxide materials can be utilized to effectively manipulate the magnetic properties of ferromagnetic metal layers in metal/oxide heterostructures[10,11,12,13], through the electric-field control of reversible redox reactions within the metal layers. Achieving high-speed performance at room temperature remains one of the main challenges before such simple architectures can be readily adopted in modern semiconductor technologies. We achieve room temperature, fast (~0.2 ms) electricfield control of the magnetic state in a Co/SrCoO2.5 heterostructure, accompanied with non-volatile bipolar resistance switching. Our result identifies an accessible and efficient strategy to realize high-speed room-temperature magnetoelectric coupling, and the hybridization between the magnetoelectric coupling and the accompanying resistance switching effect provides opportunities to design multifunctional iontronic and spintronic devices compatible with modern semiconductor technologies

Methods

Results

Conclusion