Anomalous Magneto-Electric Properties in Chalcopyrite MnGeP2 Films

We have successfully grown MnGeP2 thin films and Ge and MnGeP2 alloy films on GaAs(100) substrate. Magnetization measurements have been performed on MnGeP2 film samples at temperatures from 5 to 400 K. The measurements have shown that there are a ferromagnetic to paramagnetic transition above room temperature. Field dependent magnetization experiments have shown a coercive field of 160, 1400, 3900 Oe at 300, 250 and 5 K, respectively. A negative magnetoresistance (MR) has been found with a maximum change less than 2% at 5 T and 5 K. The MR measurements on the films have displayed hysteric behaviors with respect to the external field sweep at low fields at temperature below the ferromagnetic transition. Anomalous Hall effects have been found in the MnGeP2 film and Ge and MnGeP2 alloy film samples. Above the transition temperature neither hysteric behavior nor anomalous Hall effect was found. These results imply that spin polarized hole carriers exist in the MnGeP2 films.