Probe of Antiferromagnetic Transition Via Thermal-Excited Incoherent Spin Current

Spin Seebeck effect (SSE) for an yttrium iron garnet (YIG)/nickel oxide (NiO)/platinum (Pt) trilayer device was studied in a wide temperature range. It is found that the SSE signal is nonmonotonic in the temperature domain and shows a maximum around the Néel temperature of the NiO layer, which is similar to the temperature dependence of the spin pumping signal in the same device. This result identified that the thermal-excited incoherent spin currents are also sensitive to the fluctuation of an antiferromagnetic system and can be used to probe the antiferromagnetic phase transition. Furthermore, the antiferromagnetic NiO layer is considered to be valuable for the optimization of spin transport efficiency at YIG/Pt interface, which enhances the SSE signal around room temperature.