Pseudogap behavior of phase-separated Sm${}_{1-x}$Ca${}_x$MnO${}_3$ : A comparative photoemission study with double exchange

Abstract

Using valence band photoemission we have demonstrated the presence of a pseudogap in the near Fermi level electronic spectrum of some of the mixed phase compositions of Sm${}_{1-x}$Ca${}_x$MnO${}_3$ system. The pseudogap was found to grow in size over a large region of the phase diagram of this system, finally leading to a metal-insulator transition. We have made a study comparing the near Fermi level behaviors of this system to those of a canonical double exchange system, namely, La${}_{1-x}$Sr${}_x$MnO${}_3$. This study intends to highlight one of the important differences between the phase separated and double exchange colossal magnetoresistance systems in the nature of their energy gaps across the metal-insulator transitions. These differences could be ascribed to the distortions in the MnO${}_6$ octahedra of their structures that regulate the localization of charge carriers. We have discussed our results from the point of view of models based on the idea of phase separation.

5 pages, 4 figures

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Cited by in corpus (1)

• Pseudogap behavior in Pr${}_{0.5}$Sr${}_{0.5}$MnO${}_3$: A photoemission study