Chromium doped zinc telluride thin films with various doping concentrations are fabricated by magnetron sputtering. These films are ferromagnetic and the Curie temperature increases with Cr concentration. X-ray diffraction, transmission electron microscopy, and magnetic circular dichroism characterizations show that the films are free of ${\text{Cr}}_{1-x}{\text{Te}}_x$ impurities and the ferromagnetism is intrinsic. The transport study shows that the resistivity and magnetoresistance are governed by variable range hopping at low temperatures. A negative magnetoresistance as large as $-57\%$ is observed at 5 K. The magnetoresistance and its temperature dependence can be well explained by a model involving an increase in the localization length of carriers with a magnetic field in the hopping region. An anomalous Hall effect is also observed and a possible origin of the sign difference between the anomalous Hall resistance and ordinary Hall resistance is discussed.

• Received 14 February 2007

DOI:https://doi.org/10.1103/PhysRevB.77.155207