Spin and valence states of manganese ions in manganese-doped yttrium orthoaluminate

Two paramagnetic charge states of manganese with total electron spin of S=5/2 (Mn 2+) and S=3/2 (Mn 4+) were identified by electron paramagnetic resonance (EPR) method in Mn doped YAlO 3. In addition to the allowed ΔM S =1 spin transitions, low field forbidden ΔM S =2 transitions were observed for both Mn 4+ and Mn 2+ and ΔM S =3 transitions for Mn 2+. Relative intensities of forbidden transitions increase with a decrease of temperature and decrease with an increase of Mn concentration. The effect is due to the increase of spin–lattice and/or spin–spin relaxation times at low temperature and the decrease of spin–spin relaxation time at higher dopant concentration. Optically induced disproportionation reaction 2Mn 4+→Mn 3++Mn 5+ in YAlO 3 was studied by EPR.