Charge correlation in V$_2$OPO$_4$ probed by hard x-ray photoemission spectroscopy

TL;DR

This study uses hard x-ray photoemission spectroscopy and theoretical calculations to investigate charge ordering and transfer in V$_2$OPO$_4$, revealing large bonding-antibonding splitting and strong hybridization between V ions.

Contribution

It provides new insights into charge correlation and transfer mechanisms in V$_2$OPO$_4$ through combined experimental and theoretical analysis.

Findings

Charge ordering of V$^{2+}$ and V$^{3+}$ confirmed by HAXPES

Large energy difference indicating strong bonding-antibonding splitting

Substantial charge transfer from V$^{2+}$ to V$^{3+}$ sites

Abstract

Electronic properties of V$_2$OPO$_4$ have been investigated by means of hard x-ray photoemission spectroscopy (HAXPES) and subsequent theoretical calculations. The V 1$s$ and 2$p$ HAXPES spectra are consistent with the charge ordering of V$^{2+}$ and V$^{3+}$. The binding energy difference between the V$^{2+}$ and V$^{3+}$ components is unexpectedly large indicating large bonding-antibonding splitting between them in the final states of core level photoemission. The V 1$s$ HAXPES spectrum exhibits a charge transfer satellite which can be analyzed by configuration interaction calculations on a V$_2$O$_9$ cluster. The V 3$d$ spectral weight near the Fermi level is assigned to the 3$d$ $t_{2g}$ orbitals of the V$^{2+}$ site. The broad V 3$d$ spectral distribution is consistent with the strong hybridization between V$^{2+}$ and V$^{3+}$ in the ground state. The core level and valence band HAXPES results indicate substantial charge transfer from the V$^{2+}$ site to the V$^{3+}$ site.7 figure