A microwave absorption study in the thermochromic SrMnO3

We report electron paramagnetic resonance (EPR) and magnetically modulated microwave absorption spectroscopy (MAMMAS) studies at X-band (8.8–9.6 GHz) on powdered SrMnO3 in the 90–400 K temperature range. EPR spectrum shows one broad single-line at room temperature, which is observed only above 280.5 K, being compatible with an antiferromagnetic order. The onset of the para–antiferromagnetic transition has been determined from the temperature dependence of three main parameters extracted from the EPR spectra: resonant field (Hres), peak-to-peak linewidth (ΔHpp) and integrated intensity (IEPR). The MAMMAS response shows a change in the region 276–283 K, compatible with the para–antiferromagnetic transition, without presenting any significant change in the region of thermochromism.