[28] Electrical and optical observations of ferromagnetism in Ge_0.7Mn_0.3 semiconductor

We prepared a polycrystalline Ge_0.7Mn_0.3 thin film which exhibited large magnetization at room temperature with the ferromagnetic Curie temperature higher than 400 K. In particular, the magnetic circular dichroism spectra of the Ge_0.7Mn_0.3 thin film showed the possible application to high-temperature diluted magnetic semiconductors. We also confirmed that the hole-type Ge_0.7Mn_0.3 thin film has magneto-transport properties induced by external magnetic fields in the temperature range 10–300 K.