NMR evidence of the magnetic phase separation in ${\mathrm{Pr}}_{0.5}{\mathrm{Ca}}_{0.2}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_3$ manganite

The local ferromagnetism in ${\mathrm{Pr}}_{0.5}{\mathrm{Ca}}_{0.2}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_3$ manganite was investigated by means of ${}^{55}\mathrm{Mn}$ NMR for temperatures up to $T_C=220\mathrm{}\hspace{0.5em}\mathrm{K}.$ Below the ferromagnetic to antiferromagnetic transition NMR detects a minority ferromagnetic phase, which gives rise to two NMR lines having comparable amplitudes. One of these lines is attributed to the volume, while the other to the boundary of the ferromagnetic microdomains. For $T>~T_N$ another line corresponding to the bulk ferromagnetism appears, which coexists with the signal from the minority ferromagnetic phase. All NMR signals display conspicuous thermal hysteresis of the amplitude, reflecting the first-order character of the ferromagnetic $\leftrightarrow$ antiferromagnetic transition. In addition a hysteresis of the frequency of the minority ferromagnetic phase signal was also observed. The results demonstrate a specific case of the microscopic phase separation.