Magnetic and transport properties of III-V diluted magnetic semiconductor Ga1-xCrxAs

Magnetic and transport properties of Cr-based III-V diluted magnetic semiconductor Ga1-xCrxAs Cr concentrations up to x = 0.10 have been investigated. For all the films, no long-range magnetic order was observed down to 2 K. A sign of paramagnetic Curie temperature is positive, indicating that the dominant magnetic interaction between Cr atoms is ferromagnetic. The effective number of Bohr magneton is estimated to be 5.1 +/-0.4, which is close to that of Cr2+ ion. The magnetization curve shows superparamagnetic behavior at low temperatures. The radius of the local spin order in x = 0.034 is estimated to be 1.5-2.0 nm at T = 5 K and it decreases with increasing temperature. From Hall effect measurements at room temperature, the magnitude of mobility is estimated to be less than 0.5 cm(2)/V s. This low mobility strongly suggests that the hopping conductivity is dominant in Ga1-xCrxAs films. (C) 2001 American Institute of Physics.