Magnetic and electrical properties of Co2MnGa grown on GaAs (001)

The Heusler alloys are a group of magnetic materials that will form essential components in hybrid, ferromagnet-semiconductor devices that utilize spin injection. We demonstrate that such an alloy, Co2MnGa:GaAs(001) is ferromagnetic at 300 K and has controllable magnetic properties. A weak in-plane uniaxial anisotropy is observed with the easy axis along the [0,-1,1] direction. Metallic rather than semiconducting behavior is observed over a range of wafer thicknesses. The extrapolated bulk resistivity is 20 muOmega cm at 300 K and the residual resistivity ratios range from 1.15 to 1.7 depending on the wafer thickness. An anisotropic magnetoresistance of 6% at 300 K (and 8% at 1.6 K) demonstrates the importance of spin-orbit scattering in these disordered alloys. Several issues are addressed in this letter as to whether the manifestation of the predicted spin-polarized band structure and minority spin band gap can be observed. (C) 2002 American Institute of Physics.