Resonant photoemission spectroscopy studies of the magnetic phase transitions in Pr0.5Sr0.5MnO3

The valence band electronic structure of Pr0.5Sr0.5MnO3 has been investigated using resonant photoemission spectroscopies across its paramagnetic metallic (PMM)-ferromagnetic metallic (FMM)-antiferromagnetic insulator (AFMI) transition. Using bulk sensitive soft X-ray photoemission, we have confirmed the presence of a gap in the near Fermi level electronic spectrum in the charge ordering (CO) antiferromagnetic insulator (AFMI) phase. The Fermi level exhibits a rigid-band-like shift of about similar to 0.4 eV across the PMM to AFMI transition. Further, we have observed a similar shift of the Pr 4f states to higher binding energies when the sample goes to the CO-AFMI state. The spectral behavior indicates a strong charge carrier localization associated with a charge-density-wave gap related to the CO. On the other hand, the growth of spectral weight at the Fermi level in the PMM state could well be connected to the microscopic phase-separation model. (C) 2011 Elsevier B.V. All rights reserved.