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Rare-earth-transition-metal (RETM) ferrimagnets have received great attention for their small magnetic moments and fast dynamics in the development of next-generation spintronic devices. Here, we study spin Hall magnetoresistance (SMR) in the RETM ferrimagnet and heavy-metal bilayers of ${\mathrm{Co}}_{1\text{\ensuremath{-}}x}{\mathrm{Tb}}_{x}/\mathrm{Pt}$. Anomalous temperature dependence of the SMR is observed, where the SMR changes nonmonotonically and has a valley next to the magnetization compensation temperature. Additionally, we find that the SMR varies significantly for different chemical compositions of ${\mathrm{Co}}_{1\text{\ensuremath{-}}x}{\mathrm{Tb}}_{x}$ alloys. These anomalous behaviors are interpreted as the dramatically altered spin polarization of the ${\mathrm{Co}}_{1\text{\ensuremath{-}}x}{\mathrm{Tb}}_{x}$ layer near the compensation point. By deducing spin polarization from the abnormal temperature dependence of SMR, we provide a convenient way to access spin polarization of the RETM ferrimagnets. These experimental results show implications for tunable spin-current sources of RETM ferrimagnets.

The topological material of $\mathrm{C}{\mathrm{o}}_{2}\mathrm{MnGa}$ with potentially high spin polarization has attracted more and more attention, in the fields of fundamental science and spintronic applications. Here we report the electrical- and magnetotransport behaviors in epitaxial $\mathrm{C}{\mathrm{o}}_{2}\mathrm{MnGa}$ thin films. An angle-independent negative linear magnetoresistance and a negative anisotropy magnetoresistance are observed in the whole temperature range from 3 to 300 K, indicating the existence of weak spin disorder and a high spin polarization. Intriguingly, with decreasing temperature an anomalous resistivity upturn that exhibits $\ensuremath{-}{T}^{1/2}$ dependence is observed, and this phenomenon is robust under magnetic fields. Further analysis demonstrates that the three-dimensional enhanced electron-electron interaction effect is responsible for these phenomena rather than the orbital two-channel Kondo effect or other quantum interference effects, which provides deeper insight into the transport behavior of the $\mathrm{C}{\mathrm{o}}_{2}\mathrm{MnGa}$ materials.

Compensated ferrimagnetic materials such as Co–Tb and Co–Gd have been confirmed to have significant spin–orbit torque (SOT) efficiency. However, the large coercivity and a relatively small spin-mixing conductance may hinder the applications of the near compensated ferrimagnets. In this work, we investigate the SOT effect and its potential applications in Ta/Co–Tb/Pt heterostructures. Based on a Co-rich ferrimagnetic alloy, we obtain a significant SOT switching efficiency of 15 ± 1 (10−6 Oe cm2/A) and a considerable effective spin Hall angle of θ eff = 0.270 ± 0.005. Using harmonic Hall measurement, the temperature dependence of the damping-like effective field has been extracted. The SOT efficiency scales linearly with 1/Ms in the high-temperature range but significantly deviates from this linear scaling law at a lower temperature, which is near the compensation point. In the Tb rich Ta/Co–Tb/Pt SOT device, we demonstrate the functionality of a neuron and the dependence of firing possibility on the intensity of coming stimulus, which is mimicked by the SOT switching dynamics in the ferrimagnetic Co–Tb alloy.

We have investigated the magneto-transport properties of an off-stoichiometric full-Heusler alloy Co2MnAl single-crystalline film. The Co1.65Mn1.35Al (CMA) film epitaxially grown on Ⅲ–Ⅴ semiconductor GaAs substrate exhibits perpendicular magnetic anisotropy. The resistivity of the CMA film increases with the temperature T decreasing from 300 to 5 K, showing a semiconducting-like transport behavior. Different activation energies are found in three temperature regions with transition temperatures of 35 and 110 K. In the meanwhile, the remanent magnetization can be described by T 3/2 and T 2 laws in the corresponding medium and high T ranges, respectively. The transition at around 110 K could be attributed to the ferromagnetism evolving from localized to itinerant state. The Curie temperature of the CMA film is estimated to be ~640 K. The intrinsic anomalous Hall conductivity of ~55 Ω–1cm–1 is obtained, which is almost twenty times smaller than that of Co2MnAl.