Magnetic and magnetotransport properties of solid phase epitaxially grown Si:Ce films.

Magnetic and magnetotransport properties of a magnetic semiconductor, Si:Ce films, were investigated. The as-deposited films exhibit n-type conduction due to their amorphous nature, with a temperature dependence of the resistivity (ρ-T) like a normal semiconductor with diamagnetic properties. By annealing at 973 K, the conduction and the magnetic susceptibility change to the p-type and become positive, respectively. The change in the magnetic susceptibility (χ-T) at a low magnetic field of 750 Oe against the measurement temperature exhibits spin-glasslike behavior showing a cusp around 38 K (T[sub g]). The ρ-T curve increases exponentially from 273 K to 35 K, and then drastically decreases by three orders of magnitude below 33 K. Above T[sub g], the magnetoresistance behavior at a magnetic field below 0.5 T can be understood as that of a semiconductor caused by the Lorentz force. Below T[sub g], on the other hand, an extremely large magnetoresistance, which can not be explained by a Lorentz force alone, is observed. [ABSTRACT FROM AUTHOR]