Highly Efficient Spin Transport in a Paramagnetic Insulator at Room Temperature

Abstract The exploration of new materials exhibiting excellent spin transport properties, particularly those capable of efficiently transmitting pure spin currents at room temperature, is a crucial aspect of spintronics. This work reports the observation of room‐temperature spin transport in a paramagnetic insulator Gd3Ga5O12 (GGG). By measuring the longitudinal spin Seebeck voltage, spin Hall magnetoresistance, and anomalous Hall resistance in a Y3Fe5O12 (YIG)/GGG/Pt heterostructure at room temperature, the spin current is found to propagate in GGG up to a distance of 7 nm through the paramagnons, which are the collective excitations of the local spin within the paramagnet. Remarkably, this spin propagation phenomenon occurs at a small magnetic field and irrespective of whether the spin current injected into GGG is thermally induced from YIG or electrically generated through the spin Hall effect of Pt. Moreover, the inclusion of a thin GGG spacer layer increases the thermal spin current from YIG to Pt by 31%. Calculations based on the diffusive magnon transport model indicate high spin conductance at the GGG/Pt interface. These findings highlight the potential of a wide range of paramagnetic materials in facilitating spin transport and advancing the development of spintronic devices.