Enhancing large effective spin-torque efficiency in MnRh by magnetic phase transition

We have experimentally confirmed the large enhancement of effective efficiency in charge-spin conversion through paramagnetic–antiferromagnetic phase transition in a MnRh film. Direct current-tuned spin torque-ferromagnetic resonance measurement indicates that the effective spin Hall angle (θDL) of MnRh film near phase transition temperature (150 K) is in the value of 0.046. Notably, θDL is 360% higher than that at room temperature. Experimental results indicate that large enhancement of θDL attributed to spin fluctuation during phase transition not only improves the intrinsic spin Hall effect but significantly amplifies the spin transmittance. In addition, the spin diffusion length is basically independent of temperature, indicating that the spin dephasing effect related to magnetic order has little influence on spin propagation in antiferromagnetic MnRh. This work further reveals a method to enhance effective spin-torque efficiency by large improvement of interfacial spin conductance during phase transition and provides theoretical guidance for the application of spin–orbit torque devices.