Probing Interfacial Spin Dynamics and Temperature Dependent Asymmetry in Spin Pumping Across Ni80Fe20/Cu/Cr1.12Te2 Interfaces

TL;DR

This work addresses temperature-dependent interfacial spin transport in a Py/Cu/Cr1.12Te2 trilayer, leveraging spin pumping to probe how Cr1.12Te2’s magnetic phase modulates spin current absorption and back-pumping. Broadband and cryogenic FMR quantify fundamental parameters such as the effective damping $\alpha_{eff}$, gyromagnetic ratio $\gamma$, and interfacial spin mixing conductance $g^{\uparrow\downarrow}$, with room-temperature measurements showing efficient Py-to-Cr1.12Te2 spin transfer ($g^{\uparrow\downarrow}\approx$ $1.67$–$1.72\times10^{18}\ \mathrm{m^{-2}}$) and spin current densities of $J_s\approx0.242$–$0.298\ \mathrm{MA/m^{2}}$. As temperature lowers toward the Cr1.12Te2 Curie point, the Cr1.12Te2 layer transitions from a spin sink to a spin source, enhancing damping in Py via back-pumped spin current and producing decoupled resonance modes at intermediate temperatures. The Cu spacer ensures high spin transparency and regulates interfacial coupling, enabling thermally tunable, nonreciprocal spin transport with potential for low-power spintronic devices in vdW magnetic heterostructures. Key quantitative relations include $\Delta H = (4\pi \alpha_{eff}/\gamma) f + \Delta H_0$ and the Kittel relation $f = (\gamma/2\pi)\sqrt{(H_{res}+H_K)(H_{res}+H_K+4\pi M_{eff})}$, each used to extract magnetic parameters and track their temperature dependence.

Abstract

Spin transfers in magnetic multilayers offers a promising pathway toward ultrafast, energy-efficient spintronic devices. In this study, we investigate the interfacial spin pumping and temperature-dependent spin current exchange in a Cr1.12Te2/Cu/Ni80Fe20 (Py)(FM1/NM/FM2) trilayer structure. Using broadband and cryogenic ferromagnetic resonance (FMR) measurements, we investigate key magnetization dynamical parameters, including the effective Gilbert damping factor, effective magnetic fields, interfacial spin mixing conductance, and spin current density. Efficient spin angular momentum transfers from Py to Cr1.12Te2 are observed at room temperature. At lower temperatures, the enhanced linewidth reflects temperature dependent spin pumping effects occurring at distinct precession frequencies of the ferromagnetic layers. Notably, the absence of interfacial Damping indicates that spin pumping can be modulated by controlling the net spin current flow. These findings offer critical insight into temperature-dependent tunable spin transport mechanisms in magnetic multilayers, highlighting their potential for next-generation spintronic applications.

Figures (8)

• Figure 1: (a) XRD pattern of $\mathrm{Cr_{1.12}Te_{2}}$. (b) and crystal structure of $\mathrm{Cr_{1.12}Te_{2}}$ (c) EDX spectrum of single crystal.
• Figure 2: (a) Shows $\chi(T)$ along (a) $H \parallel ab$ (b) $H \parallel c$. M(H) curves along (c) $H \parallel ab$ and (d) $H \parallel c$ measured at 2 K and 300 K.
• Figure 3: (a) FMR spectra recorded on (a) $\mathrm{Si/SiO_{2}}$/Py(10 nm), (b) Py(10 nm)$\mathrm{/Cr_{1.12}Te_{2}}$ and (c) Py(10 nm)/Cu(2 nm)$\mathrm{/Cr_{1.12}Te_{2}}$ samples. Symbols are experimental data points, and the black solid line is the fitting using Eq. \ref{['eq1']}.
• Figure 4: (a) Linewidth ($\Delta \mathrm{H}$) vs. frequency ($\mathrm{f}$) for Py(10 nm), Py(10 nm)/Cu(2 nm), Py(10 nm)$\mathrm{/Cr_{1.12}Te_{2}}$ and Py(10 nm)/Cu(2 )/$\mathrm{Cr_{1.12}Te_{2}}$ samples. The data points are extracted from FMR fittings, and the solid lines are the fittings corresponding to the linewidth equation (Eq. \ref{['eq2']}). (b) Resonance field $\mathrm{H}_{\mathrm{res}}$ vs. frequency $\mathrm{f}$ for all the samples. Black solid lines are the fits using Eq. \ref{['eq3']}.
• Figure 5: FMR spectra were recorded for the Py/Cu/$\mathrm{Cr_{1.12}Te_2}$ sample at (a) 300 K, (b) 250 K, and (c) 225 K.