Effect of growth temperature on magnetic and electronic properties of epitaxially grown MnAs thin films on GaAs(100) substrates

We grew epitaxial MnAs thin films on GaAs(100) substrates using molecular-beam epitaxy and investigated the growth temperature dependences of their physical properties. With increasing growth temperature from 200 degrees C to 350 degrees C, the crystal orientation of the film changed from type-A to type-B. The Curie temperatures of all type-B samples were similar to 346 K, while the type-A sample showed a lower bulk-like value of similar to 318 K, indicating an improvement in magnetic properties. Samples grown at above 550 degrees C exhibited semiconducting behavior, whereas the lower temperature grown samples show metallic behavior as expected. Our results indicate that growth temperature plays an important role in determining the crystal structure, magnetic, and electrical-transport properties of MnAs/GaAs(100) thin films. (C) 2013 AIP Publishing LLC.