Paramagnetic resonance and near-infrared optical absorption of SrTiO₃:Ir⁴⁺

Abstract

The ESR of the first 5d ion (5d5 in a strong cubic crystal field) identified in SrTiO3, Ir4+, is observed at g approximately=1.6 with a slight temperature-dependent tetragonal anisotropy. Due to high covalency, the orbital reduction factor is rather small: k=0.5 to 0.7, meaning that the amplitude of the wavefunction is higher at the ligands than at the central ion, in line with recent results for covalent semiconductors.