Toward room temperature ferromagnetism of Ge:Mn systems

We investigate the magnetic properties of Mnx Ge1x =Ge(1 0 0) films. We show that the choice of growth temperature and Mn content is crucial for achieving optimal magnetic performance. With a substrate temperature of 160C during film deposition, and Mn concentration between 2.7% and 4.4%, hysteresis is observed up to about 250 K. However, the magnetic loop maintains a saturating behaviour at high fields up to room temperature. For larger Mn concentrations the magnetic response is strongly suppressed, suggesting a possible segregation of manganese.