Spin/Orbital Pattern-Dependent Polaron Absorption in Nd(1-x)Sr(x)MnO3
  We investigated optical properties of Nd(1-x)Sr(x)MnO3 (x= 0.40, 0.50, 0.55, and 0.65) single crystals. In the spin/orbital disordered state, their conductivity spectra look quite similar, and the strength of the mid-infrared absorption peak is proportional to x(1-x) consistent with the polaron picture. As temperature lowers, the Nd(1-x)Sr(x)MnO3 samples enter into various spin/orbital ordered states, whose optical responses are quite different. These optical responses can be explained by the spin/orbital ordering pattern-dependent polaron hopping. 
M. W. Kim, J. H. Jung, K. H. Kim, H. J. Lee, Jaejun Yu, T. W. Noh, and   Y. Moritomo