Spin Current Generation Using a Surface Acoustic Wave Generated via Spin-Rotation Coupling

Abstract

We demonstrate the generation of alternating spin current (SC) via spin-rotation coupling (SRC) using a surface acoustic wave (SAW) in a Cu film. Ferromagnetic resonance caused by injecting SAWs was observed in a Ni-Fe film attached to a Cu film, with the resonance further found to be suppressed through the insertion of a SiO_{2} film into the interface. The intensity of the resonance depended on the angle between the wave vector of the SAW and the magnetization of the Ni-Fe film. This angular dependence is explicable in terms of the presence of spin transfer torque from a SC generated via SRC.

Fate of spin polarization in a relativistic fluid: An entropy-current analysis

“…Therefore, we conclude that even if finite spin density is presented in a relativistic fluid, it will be damped out after characteristic time scales τ s ≡ 1/D s and τ b ≡ 1/D b . 4 When τ s and τ b take large enough values compared with the typical microscopic time scale in a problem, spin hydrodynamics may work with the spin density being a quasi-conserved quantity. This means that such slow dynamics is captured by our new transport coefficients, the rotational viscosity γ and boost heat conductivity λ [cf., Eq.…”

“…Established frameworks include the low-energy effective theory from the local Gibbs distribution [26][27][28], the kinetic theory based on the Wigner function formalism [29,30], and the multi-moment formalism within the Boltzmann transport theory [31] (see references therein). c Finally, we note that the spin hydrodynamic equations can be applied, for example, to describe the QGP created in relativistic heavy-ion collisions and to the spintronics 4 Note that τs and τ b are different from each other due to the absence of the Lorentz symmetry. of emergent relativistic quasiparticles in condensed matter physics.…”

Unidirectional Pumping of Phonons by Magnetization Dynamics

“…Introduction.-Surface acoustic waves (SAWs) on the surface of high-quality piezoelectric crystals are frequently employed for traditional signal processing [1,2], but are also excellent mediators for coherent information exchange between distant quantum systems such as superconducting qubits and/or nitrogen-vacancy centers [3][4][5][6]. Piezoelectrically excited coherent SAWs drive the ferromagnetic resonance (FMR) by magnetostriction [7][8][9][10][11][12][13], excite spin waves parametrically [14], and generate electron spin currents by the rotation-spin coupling [15,16]. Conventional insulators often have good acoustic quality but only small piezoelectric effects, rendering the direct excitation, manipulation, and detection of the coherent SAWs challenging.…”

Magneto-optical detection of spin accumulation under the influence of mechanical rotation

“…After submitting this manuscript, Kobayashi et al . 15 reported a noble method of detecting spin currents generated by using Rayleigh-type surface acoustic wave (SAW) in Ni 81 Fe 19 /Cu bilayer system. By measuring microwave absorption at SAW excitation frequency at 1.5 GHz, a large spin-rotation coupling effect was observed.…”