Field-Free Magnetization Switching by an Acoustic Wave

Abstract

Surface acoustic waves (SAW) propagating on magneto-strictive ferromagnets can induce magnetization reversal: their weak damping and mature technology make them ideal for remote wave control of magnetic bits. Experimental demonstrations of this spectacular coupling have so far required the simultaneous application of a static magnetic field. We show here SAW-driven allacoustical switching (AAS) over millimetric distances. It relies on the triggering of magnetization precession of a uniaxial in-plane magnetized film by acoustic ferromagnetic resonance at zero field. Moreover, the absence of biasing field enables toggling between the two equilibrium magnetic states for over twenty consecutive acoustic pulses. This proof-of-concept opens an alternative path to magnetic bit manipulation.

Phonon Transport Controlled by Ferromagnetic Resonance

“…Elastically driven ferromagnetic resonance (FMR) is at the core of combining straintronics and spintronics [1][2][3][4][5], which is drawing much attention due to both interesting fundamental physics and potential applications. This includes among others, elastically driven spin pumping [6,7], phonon driven inverse Edelstein effect [8] and field-free magnetization switching [9]. Recently, several studies on magnons-phonons interconversions have emerged [10][11][12][13][14].…”

“…In particular, theoretical models were developed in order to provide a microscopic understanding of how magnon-phonon interaction influences the damping and transport of magnons [13,15]. The mechanisms for the coupling between phonons and magnons in ferromagnetic materials include, magnetostriction [1][2][3][4][5][6][7][8][9]16] and spin-rotation coupling [14,17,18]. The latter mechanism is a manifestation of the Einstein-de Haas and Barnett effects corresponding to the transfer of the angular momentum between spin and mechanical degrees of freedom [19][20][21].…”

Surface-Acoustic-Wave Induced Ferromagnetic Resonance in Fe Thin Films and Magnetic Field Sensing

“…Later, MEC in the subgigahertz regime allowed SAWinduced ferromagnetic resonance (FMR) to be observed in Ni [11], (Ga,Mn)(As,P) [12] and (Ga,Mn)As [13] thin films. Indeed, resonant MEC is so efficient that spinpumping effects could be generated in a Co/Pt bilayer at 1.5 GHz [14], and magnetization of (Ga,Mn)(As,P) or (Ga,Mn)As thin films could be irreversibly switched [15][16][17].…”

Acoustic-Wave-Induced Ferromagnetic-Resonance-Assisted Spin-Torque Switching of Perpendicular Magnetic Tunnel Junctions with Anisotropy Variation

“…Previously, SAW driven FMR on Ni film [9] and magnetization switching for magnetostrictive Co nanomagnets has been experimentally reported [10]. Precessional magnetization switching [11] with SAW on (GA, Mn) (AS, P) film and field free switching with SAW for (Ga, As) P [12] has also been experimentally reported at low temperature. Laser pump induced SAW and their magnetization dynamics has been studied for single nanomagnet [13] and on patterned periodic nanodots [14] and their magnetization reversal has been numerically investigated in nanomagnets [15].…”