Raman-active phonons andNd3+crystal-field studies of weakly dopedNd1−xSrxMnO3

Abstract

Raman-active phonons as a function of temperature and ${\mathrm{Nd}}^{3+}$ infrared active crystal-field excitations under high magnetic fields have been studied in ${\mathrm{Nd}}_{0.975}{\mathrm{Sr}}_{0.025}{\mathrm{MnO}}_{3}$ and ${\mathrm{Nd}}_{0.9}{\mathrm{Sr}}_{0.1}{\mathrm{MnO}}_{3}$ and compared to ${\mathrm{NdMnO}}_{3}$ results. While long range antiferromagnetism disappears in ${\mathrm{Nd}}_{0.9}{\mathrm{Sr}}_{0.1}{\mathrm{MnO}}_{3}$, low energy phonon softening and phase separation in domains develop as a result of doping. Calculation of $g$ tensors indicates that additional crystal-field excitations observed in ${\mathrm{Nd}}_{0.975}{\mathrm{Sr}}_{0.025}{\mathrm{MnO}}_{3}$ and ${\mathrm{Nd}}_{0.9}{\mathrm{Sr}}_{0.1}{\mathrm{MnO}}_{3}$ are due to $x\text{\ensuremath{-}}y$ twinning.