Stoichiometric growth of high Curie temperature heavily-alloyed GaMnAs

Heavily-alloyed, 100 nm Ga1-xMnxAs (x>0.1) films are obtained via low temperature molecular beam epitaxy utilizing a combinatorial technique which allows systematic control of excess arsenic during growth. Reproducible, optimized electronic, magnetic and structural properties are found in a narrow range of stoichiometric growth conditions. The Curie temperature of stoichiometric material is 150-165 K and independent of x within a large window of growth conditions while substitutional Mn content increases linearly, contradicting the prediction of the Zener Model of hole-mediated ferromagnetism.