Structural and magnetoresistive properties of magnetic tunnel junctions with half-metallic Co2mnAl

A series of polycrystalline full-Heusler Co2MnAl thin films were deposited on Si (100) coated with thermo SiO2 by using different types of seed layers such as Cr, Mg, MgO∕Cr, and MgO. The properties of the Co2MnAl thin films such as the coercivity, atomic composition, and crystalline structure strongly depend on the deposition conditions and seed layers. Very soft Co2MnAl thin films with coercivity of 8.3Oe and small magnetostriction coefficient λS=1.43×10−5 had been obtained when MgO was used as seed layer. Magnetic tunnel junctions with magnetoresistance ratio of 12%–19% by utilizing the Co2MnAl as bottom ferromagnetic electrode have been successfully fabricated.