Efficient Modulation of Magnon Conductivity in Y3Fe5O12 Using Anomalous Spin Hall Effect of a Permalloy Gate Electrode

Abstract

We report the control of the modulation efficiency of the magnon conductivity in yttrium iron garnet (YIG) using magnon spin injection from a ferromagnetic metal permalloy (Py) used as a modulator in a three-terminal magnon transistor geometry. The modulation efficiency is estimated by means of nonlocal spin-transport measurements between platinum injector and detector strips. A charge current is sent through the Py modulator to create a spin accumulation at the YIG-Py interface via the spin Hall effect and the anomalous spin Hall effect (ASHE). We observe an enhancement of the modulation efficiency for the electrically generated magnons from 2.5%/mA at 10 mT to 4.7%/mA for magnetic fields higher than 50 mT. That enhancement is attributed to the ASHE, which is maximized when the Py magnetization is perpendicular to the charge current. However, the modulation efficiency of the thermally generated magnons exhibits an opposite behavior, 12.0%/mA at 10 mT to 6.6%/mA at 50 mT, which disagrees with what we expect from the ASHE contribution to the modulation.

A puzzling insensitivity of magnon spin diffusion to the presence of 180-degree domain walls

“…At the coercive fields, the signals for both orientations approach about half of the maximum signal. This behavior appears to be similar to some previous observations reported in nickel ferrite 5 and in YIG 42 , which could be attributed to a mixture of the reduced magnon injection and the magnon scattering at domain walls. Due just to the efficiency of magnon injection and detection for a magnetization easy axis oriented 45° from the propagation direction, we would indeed expect R 1 ω /R 1max = sin 2 (45°) = 1 / 2.…”

All‐Electrical Magnon Transport Experiments in Magnetically Ordered Insulators

“…In this regard, all-electrical magnon transport experiments already showed that they are beneficial to qualitatively and quantitatively investigate charge-to-spin current conversion processes in magnetically ordered conductors. [69,74,95,101,104] As a next step, we have to describe the transfer of spin momentum at the interface between the NM and the MOI. A detailed theoretical description is presented in the study by Bender et al [105] including heat transport across the NM/MOI interface.…”

“…[203] In addition, similar effects have been observed using a ferromagnetic metal as the modulator strip. [104] Hopefully more experiments and a better theoretical understanding of the nonequilibrium and chaotic processes at work (especially in the regime beyond magnetic damping compensation) allow further exploration of the regime of spin superfluidity and magnon BoseÀEinstein condensates via all-electrical magnon transport experiments in MOIs at the nanoscale.…”

Magnon transport in $\mathrm{\mathbf{Y_3Fe_5O_{12}}}$/Pt nanostructures with reduced effective magnetization

“…The MOI yttrium iron garnet (Y 3 Fe 5 O 12 , YIG) is a promising candidate for hosting efficient magnon based spin transport due to its low Gilbert damping parameter even in nanometer-thin films [5] and its correspondingly large magnon propagation length [6][7][8][9]. Amongst the device concepts enabling logic operation with magnonic spin currents, transistorinspired devices and even logic gates have been demonstrated [4,[10][11][12][13]. Such transistor-like device concepts generally rely on spin-transfer torque for spin current generation.…”