Magnetic and electronic properties of be-doped low-temperature grown GaAs layers

Magnetic and electron transport properties of Be-doped low-temperature-grown GaAs layers at low temperatures were studied. A nearly abrupt decrease of magnetization is observed at a temperature around 3.2 K where a discontinuous decrease in resistance is also observed. These observations are explained by cooperative transition of the electron states of AS_Ga defects. First-principal calculations of the electron state of an AS_Ga atom with a shallow acceptor Be atom show that at the transition, an AS_Ga⁺ion is displaced to the interstitial site and becomes a neutral atom, leading to a magnetization annihilation. In addition, the displacement results in the generation of a hole in the valence band and enhance the electrical conduction.