Abstract
By linking the dynamics of local piezostrain to the dynamics of local magnetization, we computationally analyzed the speed of a recently proposed scheme of piezostrain-mediated perpendicular magnetization reversal driven by a voltage pulse in magnetoelectric heterostructures. We used a model heterostructure consisting of an elliptical ultrathin amorphous Co20Fe60B20 on top of a polycrystalline Pb(Zr,Ti)O3 (PZT) thin film. We constructed a diagram showing the speed of perpendicular magnetization reversal as a function of the amplitude of the applied voltage pulse and the stiffness damping coefficient of PZT film. In addition, we investigated the influence of thermal fluctuations on the switching speed. The analyses suggest that the switching time remains well below 10 ns and that the energy dissipation per switching is on the order of femtojoule. The present computational analyses can be generally used to predict the speed of piezostrain-enabled magnetization switching and magnetic domain-wall motion, which critically determines the response time of corresponding piezostrain-enabled spintronic and magnonic devices.
Highlights
Magnetoelectric coupling in magnetic/dielectric heterostructures enables ultralow-power spintronic devices by using a non-powerdissipating electric field to control the directions and/or the transport of spins.[1,2,3] One well-pursued scheme is to use an electric field to reverse the magnetization, suggesting applications in magnetic memories[2] and logic gates.[4]
A larger energy barrier will lead to a higher thermal stability of the initially perpendicular magnetization, a larger strain will be required to switch the initially perpendicular magnetic easy axis (EA) to the inplane long axis
Switching speed Using computational modeling of the temporal strain evolution in the PZT film on application of a 0.97- ns-duration voltage pulse and the magnetization dynamics under such a dynamically changing strain, we demonstrated a magnetization reversal time as low as 2.5 ns
Summary
Magnetoelectric coupling in magnetic/dielectric heterostructures enables ultralow-power spintronic devices by using a non-powerdissipating electric field to control the directions and/or the transport of spins.[1,2,3] One well-pursued scheme is to use an electric field to reverse the magnetization, suggesting applications in magnetic memories[2] and logic gates.[4]. Many experimental efforts have been made to achieve voltagedriven magnetization reversal through electrically controlled exchange coupling,[5,6,7] charge/orbital effect[8,9,10] and/or strain[11,12,13,14] across the interface of magnetic/dielectric heterostructures. He et al.[5] demonstrated an electrically controlled perpendicular magnetization reversal in ultrathin Pd/Co multilayers in the presence of a static magnetic field by electrically reversing the uncompensated surface magnetization of an adjacent magnetoelectric antiferromagnet (0001)-Cr2O3 and thereby the polarity of the exchange bias field at the multilayer/Cr2O3 interface. Heron et al.[7] directly observed a voltagedriven in-plane net magnetization reversal in an exchange-coupled
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