Nonmagnetic compensation in ferromagnetic Ga_1-xMn_xAs and Ga_1-xMn_xP synthesized by ion implantation and pulsed-laser melting

The electronic and magnetic effects of intentional compensation with nonmagnetic donors are investigated in the ferromagnetic semiconductors Ga_1-xMn_xAs and Ga_1-xMn_xP synthesized using ion implantation and pulsed-laser melting. It is demonstrated that compensation with nonmagnetic donors and Mn_I have similar qualitative effects on materials properties. With compensation T_C decreases, resistivity increases, and stronger magnetoresistance and anomalous Hall effect attributed to skew scattering are observed. Ga_1-xMn_xAs can be controllably compensated with Te through a metal-insulator transition through which the magnetic and electrical properties vary continuously. The resistivity of insulating Ga_1-xMn_xAs:Te can be described by thermal activation to the mobility edge and simply activated hopping transport. Ga_1-xMn_xP doped with S is insulating at all compositions but shows decreasing T_C with compensation. The existence of a ferromagnetic insulating state in Ga_1-xMn_xAs:Te and Ga_1-xMn_xP:S having T_C's of the same order as the uncompensated materials demonstrates that localized holes are effective at mediating global ferromagnetism in ferromagnetic semiconductors through the percolation of ferromagnetic "puddles" at low temperatures. © 2008 American Institute of Physics.