Ga_1-xMn_xP Synthesized by ion implantation and pulsed-laser melting

The synthesis of single-crystalline epitaxial thin films of the carrier-mediated ferromagnetic phase of Ga_1-xMn_xP and Ga_1-xMn_xP-based quaternary alloys using ion implantation and pulsed-laser melting (II-PLM) has allowed for the exploration of the effect of anion substitution on ferromagnetism in Ga_1-xMn_x-pnictide systems. Despite displaying significantly greater hole localization than the canonical Ga_1-xMn_xAs system many of the properties, including the dependence of the Curie temperature on x and hole concentration, X-ray absorption spectroscopy and magnetic circular dichroism lineshapes, and manipulation of the magnetic anisotropy by carrier concentration and epitaxial strain, are substantially similar in the two materials. Furthermore, the combination of far infrared photoconductivity and THz spectroscopy indicates that the carriers responsible for ferromagnetic exchange are localized within an impurity band that remains unmergedwith the GaP valence band for at least x ≤ 0.042. These remarkable findings suggest that ferromagnetism in III_1-xMn_xV materials exists on a continuum in terms of carrier localization and that localized carriers primarily of cation d character are capable of effectively mediating ferromagnetic exchange. © 2009 by Pan Stanford Publishing Pte Ltd. All rights reserved.