Vertical spin transport in MnAs/GaMnAs heterostructures

Electrical spin injection and detection across metal-semiconductor interface is an important step for practical semiconductor spintronic devices. However, the problem of huge conductance mismatch between metals and semiconductors prohibited the progress. Intensive studies were carried out to find ways to overcome this problem. The use of tunneling or Schottky barrier is one of them and turns out to be quite successful. For example, AlAs tunneling barrier at MnAs/GaMnAs interface or GaMnAs/GaMnAs interface allows efficient spin-polarized tunneling [1][2]. Here, we discuss the effect of barrier strength on the tunneling efficiency in MnAs/GaMnAs heterostructures grown by low-temperature molecular beam epitaxy. Work supported by the Korean Science and Engineering Foundation through the Center for Strongly Correlated Materials Research at Seoul National University and by the KIST Vision 21 program. [1] S. H. Chun \textit{et al}., Phys. Rev. B \textbf{66}, 100408(R) (2002) [2] M. Tanaka and Y. Higo, Phys. Rev. Lett. \textbf{87}, 026602 (2001)