PES and XAS Study on Electronic Structures of Multiferroic RMnO$_3$ (R=Y, Er)

TL;DR

This study investigates the electronic structures of multiferroic RMnO$_3$ (R=Y, Er) using PES and XAS, revealing details about Mn ion states, charge transfer characteristics, and unoccupied orbitals in different phases.

Contribution

The paper provides detailed spectroscopic analysis of RMnO$_3$, highlighting the Mn valence state, orbital occupations, and charge transfer nature, which advances understanding of their electronic structures.

Findings

Mn ions are in a high-spin trivalent state

YMnO$_3$ is likely a charge-transfer insulator

Unoccupied Mn $d_{3z^2 -r^2}$ state in ferroelectric phase

Abstract

Electronic structures of multiferroic RMnO$_3$ (R=Y, Er) have been investigated by employing photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). We have found that Mn ions in RMnO$_3$ are in the trivalent high-spin state with the total spin of S=2. The occupied Mn ($d_{xz} - d_{yz}$) states lie deep below $\rm E_F$, while the occupied Mn ($d_{xy} - d_{x^2 -y^2}$) states overlap very much with the O $2p$ states. It is observed that the PES spectral intensity of Mn 3d states is negligible above the occupied O $2p$ bands, suggesting that YMnO$_3$ is likely to be a charge-transfer insulator. The Mn $d_{3z^2 -r^2}$ state is mostly unoccupied in the ferroelectric phase of YMnO$_3$.