Formation of epitaxial MnSb and MnBi layers on GaMnAs

Janusz Kanski 1Johan Adell 1M. Adell 1,2L. Ilver 1Janusz Sadowski 2,3

1. Chalmers University of Technology, Göteborg 412 96, Sweden
2. Lund University, MAX-Lab, Lund 221 00, Sweden
3. Polish Academy of Sciences, Institute of Physics, al. Lotników 32/46, Warszawa 02-668, Poland

Abstract

GaMnAs remains to be a candidate material for future spintronics. For some time it was believed that the Curie temperature of this system would belimited toaround 110K forfundamental (but unknown) reasons. Eventually it became clear that point defects may have a detrimental influence on the magnetic properties, and that the density of defects can be reduced by different annealing treatments. Thus, several groups have been able to produce GaMnAs with ferromagnetic properties above 160K. Most importantly, it now seems that the limiting mechanisms are more of practical than fundamental nature, and it is believed that RT ferromagnetism is within reach. Since the Curie temperature is proportional to the density of charge carriers and to the density of magnetic ions, an obvious strategy would be to maximize these quantities. Unfortunately, to raise the Mn content in GaMnAs the growth temperature must be lowered, and this in turn promotes generation of point defects. Therefore, this approach is by no means trivial. An alternative way to achieve new magnetic properties is by including single or multiple layers of MnAs, MnSb, or MnBi in GaMnAs. In the present work we demonstrate that by applying post growth annealing under As capping we are able to obtain continuous epitaxial films of MnAs on GaMnAs, and by As/Sb or Bi exchange reactions also MnSb and MnBi films can be grown. The latter are particularly interesting, both being half metals with Curie temperatures far above room temperature.

 

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Presentation: Oral at E-MRS Fall Meeting 2006, Symposium E, by Janusz Sadowski
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 19:18
Revised:   2009-06-07 00:44