Researchers with the U.S. DOE's Berkeley Lab in collaboration with scientist from University of Notre Dame have determined the origin of the charge-carriers responsible for the ferromagnetic properties that make gallium manganese arsenide such a hot commodity for spintronic devices.

The study showed that the holes (positively-charged energy spaces) in gallium manganese arsenide that control the Curie temperature, the temperature at which magnetism is lost, are located in an impurity energy band rather than a valence energy band, as many scientists have argued. This finding opens the possibility of fabricating gallium manganese arsenide so as to expand the width and occupation of the impurity band and thereby boost the Curie temperature to improve spintronic potential.