Shear-strain-mediated large nonvolatile tuning of ferromagnetic resonance by an electric field in multiferroic heterostructures

Ming Zheng,Takamasa Usami,Tomoyasu Taniyama

doi:10.1038/s41427-020-00279-4

Abstract

Controlling magnetism by an electric field is of critical importance for the future development of ultralow-power electronic and spintronic devices. Progress has been made in electrically driven nonvolatile tuning of magnetic states in multiferroic heterostructures for the information storage industry, which is exclusively attributed to the ferroelectric-polarization-switching-induced interfacial charge effect or nonlinear lattice strain effect. Here, we demonstrate that a hitherto unappreciated shear strain in the ferroelectric 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 substrate triggered by an electric field can be adopted to obtain robust nonvolatile control of the ferromagnetic resonance in an elastically coupled epitaxial Fe70Rh30 thin film. The disappearance of the resonance peak in a low-field-sweeping mode and the large resonance field shift of 111 Oe upon polarization switching demonstrate a strong shear-strain-mediated magnetoelectric coupling effect. In particular, in situ Kerr measurement identifies that the nonvolatile magnetic switching purely originates from electric-field-induced 109° ferroelastic domain switching rather than from 71°/180° ferroelectric domain switching even without the assistance of a magnetic field. This discovery illustrates the role of shear strain in achieving electrically tunable nonvolatile modulation of dynamic magnetic properties, and favors the design of future energy-efficient magnetoelectric microwave devices.

Highlights

IntroductionThe integration of magnetic thin films (e.g., metals/alloys, ferrites, manganites, and dilute magnetic semiconductors) with perovskite ferroelectrics provides a new avenue for modifying magnetism by electric fields (instead of magnetic fields and electric currents) through a strong magnetoelectric (ME) coupling effect, which shows promise for application in high-speed, lightweight, and ultralow-power tunable electronic and spintronic devices[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]
We report epitaxial integration of Fe70Rh30 (FeRh) thin films with ferroelectric PMN-PT single crystals and investigate the nonvolatile electric field effect on their ferromagnetic resonance (FMR) properties at room temperature
A good epitaxial heterointerface is crucial for electric control of the magnetism in multiferroic heterostructures that seeks to exploit strong interfacial mechanical strain coupling

Summary

Introduction

The integration of magnetic thin films (e.g., metals/alloys, ferrites, manganites, and dilute magnetic semiconductors) with perovskite ferroelectrics provides a new avenue for modifying magnetism by electric fields (instead of magnetic fields and electric currents) through a strong magnetoelectric (ME) coupling effect, which shows promise for application in high-speed, lightweight, and ultralow-power tunable electronic and spintronic devices[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. Recent efforts have been made toward electrically controlling a number of different magnetic effects in these multiferroic heterostructures, such as the tunneling anisotropic magnetoresistance[2], topological anomalous Hall effect[3], magnetic domain wall motion[6], in-plane/perpendicular magnetic anisotropy[7,8], exchange bias[10], magnetic phase transition[3,4,14] and ferromagnetic resonance (FMR)[11], as well as toward nonvolatile tuning of magnetic states[12,18]. The most common method was to utilize the remnant electric polarization of ferroelectrics to create a thin surface charge density at the interface of magnetic/ ferroelectric composites (i.e., the ferroelectric field effect), which can offer nonvolatile switching of magnetic properties in multiferroic heterostructures via a charge-driven ME coupling effect[18,19]. The electrically assisted interfacial charge effect can only be experimentally detected in ultrathin atomically flat ferromagnetic layers or at low temperatures[19], because of the infinitesimal screening length (a few unit cells) and/or large charge

Methods

Results

Conclusion