New Concept for Magnetization Switching by Ultrafast Acoustic Pulses

Abstract

It is shown theoretically that a single acoustic pulse, a few picoseconds long, can reverse magnetization in a magnetostrictive material Terfenol-D. Following giant magnetoelastic changes of free energy density, the magnetization vector is ejected from a local in-plane energy minimum and decays into another minimum. For an acoustic pulse duration significantly shorter than magnetization precession period τac≪Tprec, the switching threshold is determined by the acoustic pulse area, i.e., pulse integral in the time domain, similar to coherent phenomena in optics. Simulation results are summarized in a magnetoacoustic switching diagram and discussed in the context of all-optical magnetization switching by circularly polarized light pulses.

Surface-acoustic-wave-driven ferromagnetic resonance in (Ga,Mn)(As,P) epilayers

“…The opposite effect, inverse magnetostriction, whereby magnetization can be changed upon application of a strain, is particularly relevant to magnetic data storage technologies as a possible route towards induction-free data manipulation when used dynamically. It has been proposed for magnetization switching through resonant [2,3] or nonresonant processes [4,5], the latter possibly at play in early results of surface acoustic wave (SAW)-induced lowering of coercivity in Galfenol films [6]. In the case of precessional (resonant) switching, two features are necessary: sizable magnetoacoustic coupling (to trigger precession), and a highly nonlinear system (to force wide, noncircular precession needed for magnetization reversal).…”

Ultrafast magnetoelastic probing of surface acoustic transients

“…The elastically generated, out-ofplane torque [14,15] originates from the coupling of in-plane longitudinal strain [16], xx , to in-plane components, M x and M y , of magnetization vector:…”

Strain and Thermally Induced Magnetic Dynamics and Spin Current in Magnetic Insulators Subject to Transient Optical Grating

“…Fueled by potential applications in spintronics and sensorics thermal and magnetoelastic driven magnetic dynamics is attacking a great deal of research (Davis et al, 2010;Scherbakov et al, 2010;Roy et al, 2011;Uchida et al, 2011a;Weiler et al, 2011;Azovtsev and Pertsev, 2016). Elastic excitations might be triggered in a variety of ways, for instance via acoustic transducers (Davis et al, 2010;Uchida et al, 2011b;Weiler et al, 2011Weiler et al, , 2012Thevenard et al, 2013) or by optical methods (Scherbakov et al, 2010;Kim et al, 2012;Jäger et al, 2013;Kovalenko et al, 2013;Afanasiev et al, 2014). Optical methods mainly generate elastic excitations via laser heating and thermoelastic effects.…”