EPR of photochromic Mo3+ in SrTiO3

TL;DR

This study uses EPR spectroscopy to identify and characterize Mo3+ ions as paramagnetic centers in SrTiO3 crystals within 4.2K to 77K, providing detailed spin parameters and observing no spectral changes across the phase transition.

Contribution

It reports the first EPR characterization of Mo3+ in SrTiO3, including spin Hamiltonian parameters and temperature-dependent behavior.

Findings

Mo3+ ions are paramagnetic centers in SrTiO3.

No spectral splitting observed across the phase transition.

Precise g and hyperfine coupling constants determined.

Abstract

In single crystals of SrTiO_3, a paramagnetic center, characterized by S = 3/2 and hyperfine interaction with an I = 5/2 nuclear spin has been observed in the temperature range 4.2K-77K by means of EPR. The impurity center is attributed to Mo3+. No additional line splitting in the EPR spectrum due to the 105K phase transition has been observed. At 4.2K the following spin Hamiltonian parameters for this impurity ion were obtained: g = 1.9546\pm0.0010 and A = (32.0\pm0.05)\times10^-4 cm^-1.