EPR studies of manganese centers in SrTiO3: Non-Kramers Mn3+ ions and   spin-spin coupled Mn4+ dimers
  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. 
D. V. Azamat, A. Dejneka, J. Lancok, V. A. Trepakov, L. Jastrabik and   A. G. Badalyan
cond-mat.mtrl-sci cond-mat.other