Fermi Surfaces and $p$-$d$ Hybridization in the Diluted Magnetic Semiconductor Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$ Studied by Soft X-ray Angle Resolved Photoemission Spectroscopy

TL;DR

This study uses angle-resolved photoemission spectroscopy to analyze the electronic structure of the diluted magnetic semiconductor Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$, revealing its Fermi surfaces, band hybridization, and differences from GaMnAs.

Contribution

It provides detailed experimental insights into the electronic structure and impurity bands of Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$, highlighting differences from GaMnAs.

Findings

Identification of hole and electron pockets explaining metallic transport.

Observation of Mn $3d$ impurity band below the valence band maximum.

Strong hybridization between Mn $3d$ and As $4p$ orbitals influences ferromagnetism.

Abstract

The electronic structure of the new diluted magnetic semiconductor Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$ ($x=0.30$, $y=0.15$) in single crystal form has been investigated by angle-resolved photoemission spectroscopy (ARPES). %High density of states of nondispersive bands composed of the Zn $3d$ orbitals are observed with ultraviolet incident light. Measurements with soft x-rays clarify the host valence-band electronic structure primarily composed of the As $4p$ states. Two hole pockets around the $\Gamma$ point, a hole corrugated cylinder surrounding the $\Gamma$ and Z points, and an electron pocket around the Z point are observed, and explain the metallic transport of Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$. This is contrasted with Ga$_{1-x}$Mn$_{x}$As (GaMnAs), where it is located above the As $4p$ valence-band maximum (VBM) and no Fermi surfaces have been clearly identified. Resonance soft x-ray ARPES measurements reveal a nondispersive (Kondo resonance-like) Mn $3d$ impurity band near the Fermi level, as in the case of GaMnAs. However, the impurity band is located well below the VBM, unlike the impurity band in GaMnAs, which is located around and above the VBM. We conclude that, while the strong hybridization between the Mn $3d$ and the As $4p$ orbitals plays an important role in creating the impurity band and inducing high temperature ferromagnetism in both systems, the metallic transport may predominantly occur in the host valence band in Ba$_{1-x}$K$_{x}$(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$ and in the impurity band in GaMnAs.