Growth and magnetic and electrical-transport properties of NiAs structured Mn_(1-x)Ga_xAs thin films

摘要

We have successfully fabricated epitaxial Mn_(1-x)Ga_xAs thin films with the NiAs crystal structure on GaAs(001) substrates by molecular-beam epitaxy characterized by their magnetic and electrical-transport properties. For a sample with x=0.17, the magnetic Curie temperature (T_C) was approx 340 K, which exceeds room temperature, and a high anisotropy in the M-H hysteresis loops was observed. Furthermore, the temperature dependence of the resistance shows a semiconducting behavior with an indication of an interplay between the charge carriers and localized magnetic ions. The magnetoresistance is different from that of a MnAs film, indicating a radical alteration of electronic structure by a partial substitution of Ga for Mn in NiAs structured MnAs.