Electronic structure, growth, and structural and magnetic properties of magnetic semiconductor Fe/GaAs heterostructures

In this article we describe a study of the magnetic semiconductors of Fe/Ga As, undertaken theoretically and experimentally. We discuss the structural advantage of body-centered-cubic-Fe structure lattice matching to GaAs (001 ). Theoretical calculations using the self-consistent linear augmented-plan e-wave method indicate the existence of an energy state of the quantum well in Fe layers in a GaAs/Fe/GaAs double heterostructure. We then present the preparation of Fe/GaAs heterostructures by using molecular beam epitaxy. a lpha-Fe and delta-Fe could be grown epitaxially on (001) GaAs at a substrat e temperature of 290 and 580 degrees C, respectively, which was confirmed f rom the results of reflection high energy electron diffraction and x-ray di ffraction measurements. We also found that, in order to obtain alpha-Fe/GaA s, a low-temperature GaAs growth must be induced before the Fe growth can o ccur. Differences in magnetic properties were observed in the magnetic meas urements, indicating that alpha-Fe dominates the ferromagnetic state, while the delta-Fe shows relatively slight ferromagnetic behavior. (C) 2000 Amer ican Vacuum Society. [S0734-211X(00)12703-9].