Tunnel injection of spin-polarized current in Co2CrxFe1−xAl (x = 1, 0.6) insulator-superconductor heterostructures

F-I-S tunnel junctions of Co2CrAl-I-Pb and Co2Cr0.6Fe0.4Al-I-Pb based on films of semimetal ferromagnetic Heusler alloys Co2CrAl (Curie temperature TC ≈ 334 K) have been fabricated and the features of spin-polarized current in them studied. A theoretical model of spin blocking of the tunnel current shows that the degree of spin polarization of the conduction electrons in quasi-single crystal films of Co2Cr0.6Fe0.4Al and Co2CrAl with B2- and L21-type order is 0.91–0.97.