Tunable Spin Hall Magnetoresistance in All-Antiferromagnetic Heterostructures

We investigate the spin Hall magnetoresistance (SMR) in all-antiferromagnetic heterostructuresα-FeO/CrOwith Pt contacts.When the temperature is ultralow (<50 K),the spin current generated in the Pt layer cannot be transmitted through CrO(t=4 nm),and the SMR is near zero.Meanwhile,when the temperature is higher than the spin fluctuation temperature T(≈50 K) of CrOand lower than its Néel temperature T(≈300 K),the spin current goes through the CrOlayer and is reflected at theα-FeO/CrOinterface;an antiferromagnetic (negative) SMR is observed.As temperature increases higher than T,paramagnetic (positive)SMR mainly arises from the spin current reflection at the CrO/Pt interface.The transition temperatures from negative to positive SMR are enhanced with increasing CrOlayer thickness,accompanied by the absence of SMR signals when t=10 nm.Such a tunable SMR builds a bridge between spin transport and structures.It also enriches antiferromagnetic spintronics.