High-frequency magnetoacoustic resonance through strain-spin coupling in perpendicular magnetic multilayers

Abstract

It is desirable to experimentally demonstrate an extremely high resonant frequency, assisted by strain-spin coupling, in technologically important perpendicular magnetic materials for device applications. Here, we directly observe the coupling of magnons and phonons in both time and frequency domains upon femtosecond laser excitation. This strain-spin coupling leads to a magnetoacoustic resonance in perpendicular magnetic [Co/Pd]n multilayers, reaching frequencies in the extremely high frequency (EHF) band, e.g., 60 GHz. We propose a theoretical model to explain the physical mechanism underlying the strain-spin interaction. Our model explains the amplitude increase of the magnetoacoustic resonance state with time and quantitatively predicts the composition of the combined strain-spin state near the resonance. We also detail its precise dependence on the magnetostriction. The results of this work offer a potential pathway to manipulating both the magnitude and timing of EHF and strongly coupled magnon-phonon excitations.

Unveiling the Mechanism of Bulk Spin‐Orbit Torques within Chemically Disordered FexPt1‐x Single Layers

“…After we have excluded non‐uniformities in magnetic moment density, electron scattering strength, and exchange stiffness as the dominant mechanisms of inversion asymmetry, the lattice strain gradient is left as the most likely symmetry‐breaking mechanism for the bulk dampinglike SOT. Microscopically, a strain gradient can non‐uniformly modify the strengths of the SHE, [ 31–35 ] spin‐orbit interaction, [ 36 ] orbital polarization, [ 37 ] spin states at the Fermi level, [ 37 ] and strain‐spin coupling, [ 38 ] ultimately leading to inversion symmetry breaking in the generation and relaxation of spin current within the sample. As shown in Figure 4c, the lattice constant of the chemically disordered Fe x Pt 1‐ x indeed increases by 2.3% as x from 0.25 to 0.75, [ 39 ] suggesting a very strong strain gradient in the composition‐gradient samples.…”

Towards High-Repetition-Rate Intense Terahertz Source With Metal Wire-Based Plasma

“…ntense terahertz (THz) radiation has attracted growing interest in the research area of low-frequency excitation dynamics. Since various dynamic processes including lattice vibration, molecular/atom/ion resonance excitation, and electronic spin [1][2][3][4] both coincide with the THz band, brand-new physical perspectives are now opened such as resonant matter control by THz transients [5], strong magnonphonon coupling [6], and electron acceleration and manipulation [7][8][9][10]. Facilitating these intriguing researches requires an easily-accessible, compact, stable, and highrepetition-rate intense THz source.…”

Controlled Magnetic Isolation and Decoupling of Perpendicular FePt Films by Capping Ultrathin Cu(002) Nano-Islands

“…Thus, the nanocomposite and nanogranular ferromagnetic film structures fabricated at low-temperature conditions have attracted significant attention because of the decoupling of the intergranular interaction that could enhance the signal-to-noise ratio; therefore, they are considered more favorable for the next generation magnetic storage media [13][14][15][16][17][18][19][20][21][22][23]. Many attempts have been made to propose the effect of top or under layers; the additive effect of metal oxides and nitride elements is a successful method to control the chemical ordering, microstructure, magnetic coupling, and crystalline orientation of the L1 0 magnetic thin films to meet the requirements of industrial manufacture, especially in technologically important perpendicular magnetic materials for multifunctional device applications [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Recently, the spin Hall effect (SHE)-induced perpendicular magnetization reversal behavior is with pay significant attention due to its potential for future low-power memory and logic devices.…”

“…Recently, the spin Hall effect (SHE)-induced perpendicular magnetization reversal behavior is with pay significant attention due to its potential for future low-power memory and logic devices. So, the spin Hall systems and related perpendicular magnetic tunnel junctions could pave the way towards more actual spin-orbit torque-based non-volatile magnetic memory and strain-spin coupling for applications of programmable logic devices [36][37][38][39]42].…”