Heusler alloy Co 2 MnSi/Al 2 O 3 heterostructures on single-crystal Ge(001) substrates were prepared through magnetron sputtering for both Co 2 MnSi and Al 2 O 3 thin films as a promising candidate for future-generation semiconductor-based spintronic devices. Sufficiently high saturation magnetization 781 emu/cm 3 was obtained for the Co 2 MnSi thin film. Furthermore, the current versus voltage (I-V) characteristics showed that the tunneling conduction was dominant in Co 2 MnSi/Al 2 O 3 (2 nm)/Ge(001) heterostructure and the I-V characteristics were slightly dependent on temperature. The conductance versus voltage (dI/dV-V) characteristics indicated that the potential barrier height at the Co 2 MnSi/Al 2 O 3 interface was almost equal to that at the n-Ge/Al 2 O 3 interface for the prepared Co 2 MnSi/Al 2 O 3 /Ge(001) heterostructure
