A comparative study of the electron- and hole-doped compositions of single crystalline Nd_1−xCa_xMnO₃ (x=0.6 and 0.4) by Brillouin scattering

Abstract

In order to understand the differences between the nature of the electron- and the hole-doped compositions of rare earth manganates, properties of single crystals of Nd_1−xCa_xMnO₃ with x=0.6 and 0.4 have been investigated. In the electrical resistivity measurements, the electron-doped (x=0.6) composition shows no effect of magnetic field unlike the hole-doped (x=0.4) composition, but both exhibit similar current-induced changes. Brillouin scattering studies show that the x=0.6 and 0.4 compositions show softening of the modes on cooling the samples towards charge-ordering transitions. The strength of coupling between the e_g orbitals and the elastic strain is considerably larger in the hole-doped composition containing a larger population of Mn³⁺ ions.