EPR studies of manganese centers in SrTiO3: Non-Kramers Mn3+ ions and spin-spin coupled Mn4+ dimers

TL;DR

This study uses EPR spectroscopy to investigate manganese ions in SrTiO3 crystals, revealing different Jahn-Teller Mn3+ centers and Mn4+ dimers, enhancing understanding of their electronic states and interactions.

Contribution

It provides detailed EPR characterization of Mn3+ and Mn4+ centers in SrTiO3, including Jahn-Teller effects and spin-spin coupling, which were not previously well understood.

Findings

Identification of three types of Jahn-Teller Mn3+ centers.

Detection of Mn4+ dimers with exchange coupling.

Correlation of oxygen vacancies with Mn oxidation states.

Abstract

X- and Q-band electron paramagnetic resonance (EPR) study is reported on the SrTiO3 single crystals doped with 0.5-at.% MnO. EPR spectra originating from the S = 2 ground state of Mn3+ ions are shown to belong to the three distinct types of Jahn-Teller centres. The ordering of the oxygen vacancies due to the reduction treatment of the samples and consequent formation of oxygen vacancy associated Mn3+ centres are explained in terms of the localized charge compensation. The EPR spectra of SrTiO3: Mn crystals show the presence of next nearest neighbor exchange coupled Mn4+ pairs in the <110> directions.