Effect of Underlying Bi 2 Se 3 Surface on Magnetic Properties of Ni Films

We have investigated magnetic properties of Ni film specimens deposited either on GaAs or on Bi 2 Se 3 surfaces. The magnetization saturation field along the out-of-plane direction observed in the Hall data was weaker for the Ni/Bi 2 Se 3 sample than for the Ni/GaAs sample. On the other hand, planar Hall resistance measurements showed the larger in-plane coercive field for Ni/Bi 2 Se 3 than for Ni/GaAs. These changes of magnetic hardness observed along the out-of-plane and in-plane directions in the Ni/Bi 2 Se 3 specimen are consistent with effects arising from spin–orbit interaction at the surface of the Bi 2 Se 3 topological insulator.