Theory of the unusual doping and temperature dependence of photoemission spectra in manganitesPrabuddha Sanyal1, 2, Subhra Sen Gupta1, 3, 4, Nandan Pakhira1, 5, H. R. Krishnamurthy1, 5, D. D. Sarma1, 4, 5, 6 and T. V. Ramakrishnan1, 7
1 Centre for Condensed Matter Theory (CCMT), Department of Physics, Indian Institute of Science Bangalore 560012, India
2 Harishchandra Research Institute - Allahabad 211019, India
3 Department of Physics and Astronomy, University of British Columbia - 6224, Agricultural Road, Vancouver, BC V6T 1Z1, Canada
4 Solid State and Structural Chemistry Unit, Indian Institute of Science - Bangalore 560012, India
5 Jawaharlal Nehru Centre for Advanced Scientific Research - Bangalore 560064, India
6 Center for Advanced Materials, Indian Association for Cultivation of Science - Kolkata 700032, India
7 Department of Physics, Banaras Hindu University - Varanasi 221005, India
received 28 February 2008; accepted in final form 6 April 2008; published May 2008
published online 15 May 2008
A recent, major, puzzle in the core-level photoemission spectra of doped manganites is the observation of a 12 eV wide shoulder with intensity varying with temperature T as the square of the magnetization over a T scale of order 200 K, an order of magnitude less than electronic energies. This is addressed and resolved here, by extending a recently proposed two-fluid polaronmobile electron model for these systems to include core-hole effects. The position of the shoulder is found to be determined by Coulomb and Jahn-Teller energies, while its spectral weight is determined by the mobile electron energetics which is strongly T and doping dependent, due to annealed disorder scattering from the polarons and the t2g core spins. Our theory accounts quantitatively for the observed T dependence of the difference spectra, and furthermore, explains the observed correspondence between spectral changes due to increasing doping and decreasing T.
75.47.Lx - Manganites.
79.60.-i - Photoemission and photoelectron spectra.
71.10.-w - Theories and models of many-electron systems.
© EPLA 2008