Photoemission and X-ray Absorption Studies of the Diluted Magnetic Semiconductor Ba$_{1-y}$K$_{y}$(Zn$_{1-x}$Mn$_{x}$)$_{2}$As$_{2}$ Isostructural to Fe-based Superconductors

TL;DR

This study investigates the electronic and magnetic properties of a new diluted magnetic semiconductor, revealing Mn valence, hybridization, and the role of hole carriers in mediating ferromagnetism, using XAS and RPES techniques.

Contribution

It provides detailed spectroscopic insights into the valence state, hybridization, and magnetic interactions in Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$, a DMS isostructural to Fe-based superconductors.

Findings

Mn has valence 2+ and hybridizes with As orbitals.

Mn $3d$ states show a $d^{5}$ configuration with $S=5/2$.

Hole carriers induce ferromagnetism via local spin interactions.

Abstract

The electronic and magnetic properties of a new diluted magnetic semiconductor (DMS) Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$, which is isostructural to so-called 122-type Fe-based superconductors, are investigated by x-ray absorption spectroscopy (XAS) and resonance photoemission spectroscopy (RPES). Mn $L_{2,3}$-edge XAS indicates that the doped Mn atoms have the valence 2+ and strongly hybridize with the $4p$ orbitals of the tetrahedrally coordinating As ligands. The Mn $3d$ partial density of states (PDOS) obtained by RPES shows a peak around 4 eV and relatively high between 0-2 eV below the Fermi level ($E_{F}$) with little contribution at $E_{F}$, similar to that of the archetypal DMS Ga$_{1-x}$Mn$_{x}$As. This energy level creates $d^{5}$ electron configuration with $S=5/2$ local magnetic moments at the Mn atoms. Hole carriers induced by K substitution for Ba atoms go into the top of the As $4p$ valence band and are weakly bound to the Mn local spins. The ferromagnetic correlation between the local spins mediated by the hole carriers induces ferromagnetism in Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$