Influence of the two boundaries of the Pt layer on spin current transportation by spin Hall magnetoresistance

The spin Hall magnetoresistance effects (SMR) in four heterostructures consist of different boundaries of Pt layer has been investigated. The result in this work shows that the two boundaries of Pt layer in all heterostructures both influence the spin current absorption and reflection. The Pt/air interface would weaken the spin current absorption at the Co2FeSi/Pt interface on the other side of the Pt layer. On the contrary, the Pt/MgO(0 0 1) interface could boost the spin current absorption strongly at the Co2FeSi/Pt interface on the other side of the Pt layer. And this promotion effect is much stronger than the Co2FeSi/Pt interface on the spin current absorption at the other Co2FeSi/Pt interface. The MgO capping layer may avoid anisotropic magnetoresistance (AMR) induced SMR ratio decreasing at low temperature. This study provides a new way for modulating spin current absorption at the FM/HM interface.