Magnetic Properties and Electronic Configurations of Mn Ions in the Diluted Magnetic Semiconductor Ba${}_{1-x}$K${}_x$(Zn${}_{1-y}$Mn${}_y$)${}_2$As${}_2$ Studied by X-ray Magnetic Circular Dichroism and Resonant Inelastic X-ray Scattering

Abstract

The magnetic properties and the electronic excitations of the new diluted magnetic semiconductor Ba${}_{1-x}$K${}_x$(Zn${}_{1-y}$Mn${}_y$)${}_2$As${}_2$ have been studied by x-ray magnetic circular dichroism (XMCD) and resonant inelastic x-ray scattering (RIXS) at the Mn $L_{2,3}$ edge. The sum rule analysis of the XMCD spectra yields the net spin moment of $0.45\hat{I}{¼}_{\text{B}}$/Mn and the small orbital moment of $0.05\hat{I}{¼}_{\text{B}}$/Mn. This indicates that the Mn atoms are in the high-spin configurations of $d^5$, whereas the presence of competing ferromagnetic and antiferromagnetic interactions between the Mn ions reduces the net spin moment. RIXS spectra show broad peaks from 1 to 6 eV energy loss, which originate from the $d$-$d$ crystal field excitations of the Mn ions. Based on a comparison of the RIXS line shapes with those of Ga${}_{1-x}$Mn${}_x$As, we conclude that the ground state of Mn in Ba${}_{1-x}$K${}_x$(Zn${}_{1-y}$Mn${}_y$)${}_2$As${}_2$ consists not only of the charge-transferred $3d^5\underline{L}$ electron configuration ($\underline{L}$: ligand hole) with weakly bound holes as in Ga${}_{1-x}$Mn${}_x$As, but also of the pure $3d^5$ configuration with free holes.