Effect of Disorder and Strain on Spin Polarization of a Co2FeSi Heusler Alloy

The performance of the spintronic devices is highly dependent on spin polarization. Here, we have performed the first-principles DFT calculation for L21-ordered and B2-disordered Co2FeSi Heusler alloys along with the effect of lattice strain on spin polarization. In both cases, the spin polarization decreases, but the total magnetic moment increases. For experimental study, Co2FeSi/SiO2/p-Si heterostructures have been fabricated by growing codeposited Co2FeSi film on p-type silicon. Experimentally, we demonstrate the accumulation of spin-polarized carriers in p–Si from B2-ordered half-metal Co2FeSi film by measuring magnetic field-dependent electrical transport properties of the device using self-formed SiO2 as a tunnel barrier. Magnetic field-dependent current (I)–voltage (V) behavior of the device shows a prominent spin-valve effect at low temperature. Spin polarization of the device has been calculated by measuring the current across the heterostructure in the presence of a magnetic field.