Raman study of crystal-field excitations in ${\mathrm{Nd}}_{1.85}$${\mathrm{Ce}}_{0.15}$${\mathrm{CuO}}_4$

Eighteen Raman active crystal-field (CF) excitations were detected in ${\mathrm{Nd}}_{1.85}$ ${\mathrm{Ce}}_{0.15}$ ${\mathrm{CuO}}_4$. They correspond to transitions within the ${}_{}{}^4{}_{}{}^{}$ ${\mathit{I}}_{9/2}$, ${}_{}{}^4{}_{}{}^{}$ ${\mathit{I}}_{11/2}$, and ${}_{}{}^4{}_{}{}^{}$ ${\mathit{I}}_{13/2}$ multiplets associated with the inequivalent sites of the ${\mathrm{Nd}}^{3+}$ ion. Three sets of CF parameters which describe the observed energy spectra were derived. One of the three ${\mathrm{Nd}}^{3+}$ sets describes levels which are very similar to those observed in ${\mathrm{Nd}}_2$ ${\mathrm{CuO}}_4$ while the two others correspond to sites affected by the cerium doping. Kramers doublet splitting is also present indicating that antiferromagnetism persists in the ${\mathrm{CuO}}_2$ planes even with 7.5% cerium doping. © 1996 The American Physical Society.