Low Temperature Electrical Spin Injection from Highly Spin Polarized Co₂CrAl Heusler Alloy into p-Si

The low temperature spin accumulation in p-Si using Co₂CrAl/SiO₂ tunnel junction has been investigated in detail. The heterojunction has been fabricated using electron beam evaporation (EBE) technique. The 3-terminal contacts in Hanle geometry has been made for spin transport measurements. The electrical transport properties have been investigated at different isothermal conditions in the temperature range of 10–300 K. The current–voltage characteristics of the junction shows excellent rectifying magnetic diode like behaviour in lower temperature range (below 200 K). At higher temperature, the junction shows nonlinear behaviour without rectifying characteristics. We have observed spin accumulation signal in p-Si semiconductor using SiO₂/Co₂CrAl tunnel junction in the low temperature regime (30–100 K). Hence the highly spin polarized Full Heusler alloys compounds, like Co₂CrAl etc., are very attractive and can act as efficient tunnel device for spin injection in the area of spintronics devices in near future. The estimated spin life time is τ = 54 pS and spin diffusion length inside p-Si is L _SD = 289 nm at 30 K for this heterostructure.