Electronic structure of the dilute magnetic semiconductor Ga1−xMnxP from hard x-ray photoelectron spectroscopy and angle-resolved photoemission

Abstract

We have investigated the electronic structure of the dilute magnetic semiconductor (DMS) $\mathrm{G}{\mathrm{a}}_{0.98}\mathrm{M}{\mathrm{n}}_{0.02}\mathrm{P}$ and compared it to that of an undoped GaP reference sample, using hard x-ray photoelectron spectroscopy (HXPS) and hard x-ray angle-resolved photoemission spectroscopy (HARPES) at energies of about 3 keV. We present experimental data, as well as theoretical calculations, to understand the role of the Mn dopant in the emergence of ferromagnetism in this material. Both core-level spectra and angle-resolved or angle-integrated valence spectra are discussed. In particular, the HARPES experimental data are compared to free-electron final-state model calculations and to more accurate one-step photoemission theory. The experimental results show differences between $\mathrm{G}{\mathrm{a}}_{0.98}\mathrm{M}{\mathrm{n}}_{0.02}\mathrm{P}$ and GaP in both angle-resolved and angle-integrated valence spectra. The $\mathrm{G}{\mathrm{a}}_{0.98}\mathrm{M}{\mathrm{n}}_{0.02}\mathrm{P}$ bands are broadened due to the presence of Mn impurities that disturb the long-range translational order of the host GaP crystal. Mn-induced changes of the electronic structure are observed over the entire valence band range, including the presence of a distinct impurity band close to the valence-band maximum of the DMS. These experimental results are in good agreement with the one-step photoemission calculations and a prior HARPES study of $\mathrm{G}{\mathrm{a}}_{0.97}\mathrm{M}{\mathrm{n}}_{0.03}\mathrm{As}$ and GaAs [Gray et al., Nat. Mater. 11, 957 (2012)], demonstrating the strong similarity between these two materials. The Mn $2p$ and $3s$ core-level spectra also reveal an essentially identical state in doping both GaAs and GaP.