Electronic and magnetic properties of structural defects in SrTiO$_3$(Co)

TL;DR

This study investigates the structural, electronic, and magnetic properties of cobalt defects in SrTiO3, revealing how synthesis conditions influence cobalt site occupancy and oxidation states, supported by experimental and computational analyses.

Contribution

It provides new insights into cobalt defect configurations in SrTiO3 and correlates synthesis conditions with cobalt's structural and electronic states.

Findings

Co at A site is off-center by 1.0 Å

Co exists as Co2+ at A site and Co3+ at B site

Defects' properties align with experimental observations

Abstract

The synthesis conditions of SrTiO$_3$(Co) samples in which cobalt predominantly enters the $A$ or $B$ sites of the perovskite $AB$O$_3$ structure are found. EXAFS studies show that the Co impurity at the $A$ site is off-center and is displaced from the site by 1.0 {\AA}. XANES studies reveal two predominant oxidation states of Co: Co$^{2+}$ at the $A$ site and Co$^{3+}$ at the $B$ site. First-principles calculations of a number of possible cobalt-containing structural defects reveal defects whose properties are compatible with the experimentally observed Co oxidation state, its local structure, magnetic, electrical, and optical properties.