Observation of magnetic inhomogeneities in crystalline-doped manganites by electron magnetic resonance

Electron magnetic resonance measurements were employed for studying the magnetic spin structure in bulk and crushed crystalline samples of doped ${\mathrm{La}}_{0.888}{\mathrm{Na}}_{0.113}{\mathrm{Mn}}_{0.997}{\mathrm{O}}_3$ and ${\mathrm{La}}_{0.833}{\mathrm{Sn}}_{0.126}{\mathrm{Mn}}_{0.997}{\mathrm{O}}_3,$ and self-doped ${\mathrm{La}}_{0.94}{\mathrm{Mn}}_{0.98}{\mathrm{O}}_3,$ grown by fused-salt electrolysis. The ferromagnetic resonance exhibits a common characteristic multiline spectrum for single crystals and “noiselike” oscillations superimposed on ferromagnetic signal for crushed crystals. A coexistence of ferromagnetic and electron paramagnetic resonance signals was observed in a wide temperature range around $T_c.$ The results obtained are discussed regarding the presence of inherent magnetic inhomogeneities in studied manganites.