Drop of Spin Polarization of Half Metal due to Interfacial Spin Mixing

Abstract

Half metal is a ferromagnetic metal that act as a conductor to electrons with of one spin orientation, while act as an insulator for the opposite spin. Because of this high spin-dependent property, half metals are widely studied in spiritroriics area. This property can be represented by the spin polarization P = (G↑ — G↓) / (G↑ + G↓) of its spin-dependent conductances G↑,↓. The value of P of an ideal half metal is 1. However, the value of P is reduced when it is attached to other material. We study how the spin current generations that occurs at the interface of half metal and normal metal reduces the value P. At the interface of a half metal and a normal metal a spin current can be pumped from the ferromagnetic layer to the normal metal. This spin pumping effect is characterized by spin-mixing conductance, which represents the magnitude of the generated spin current due to the mixing of electrons with spin up and down. By analyzing the coupling of spin and electric currents in the interface of half metal and normal metal, we show that the spin mixing strongly influences the spin-dependent transport near the interface, and therefore reduces the spin polarization of the half metal.