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

Abstract

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.

Disordered spin gapless semiconducting CoFeCrGa Heusler alloy thin films on Si (100): experiment and theory

“…The difference in the experimentally observed magnetic moment and electronic transport from the DFT findings can be attributed to the presence of other (hkl) planes on the surface and also the point-defects (site and antistites disorders, and vacancies) present in the thin films. [65][66][67][68][69] Fig. 10 Consideration of such disorder for DFT-calculations for the thin film geometry in the CFCG alloy is beyond the scope of the present investigations.…”

Large Thermo-Spin Effects in Heusler Alloy-Based Spin Gapless Semiconductor Thin Films

“…Although it is evident from the XRD measurements that both (111) and (200) diffraction peaks are present in our MgO/CoFeCrGa (95 nm) film that rules out the possibility of complete A2 or B2 disorder, it is plausible that partial disorder and defects (antistite disorders, vacancies, etc.) are present in our film. ,− We have performed ρ xx ( T ) measurements on two additional MgO/CoFeCrGa films with 200 and 50 nm thicknesses, as shown in the Supporting Information (Figure S3). Although both MgO/CoFeCrGa (200 nm) and MgO/CoFeCrGa (50 nm) films exhibit negative temperature coefficient similar to the MgO/CoFeCrGa (95 nm) film at low temperatures, they show distinct temperature dependence.…”