https://doi.org/10.1140/epjb/e2011-10945-0
Optical investigation of LaMnO3 thin films: a study of the 2-eV band
1
CNR-SPIN and Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy
2
CNR-SPIN and Dipartimento di Scienze Fisiche, Universitá degli Studi Federico II Complesso Universitario di Monte Sant'Angelo via Cinthia, 80126 Napoli, Italy
3
CNR-SPIN and Dipartimento di Fisica E.R. Caianiello, Università di Salerno, via Ponte don Melillo, 84084 Fisciano, Italy
Corresponding author: a alessandro.nucara@roma1.infn.it
Received:
2
December
2010
Revised:
11
January
2011
Published online:
9
February
2011
We measure the transmittance of LaMnO3 (LMO) thin films in the spectral range from 10 000 to 38 000 cm-1 as a function of temperature. The optical conductivity obtained from the transmittance data is decomposed into five Drude-Lorentz contributions: three of them show evident changes below the Néel temperature TN 140 K. We discuss the band assignment in the framework of the tight-binding and of the orbitally degenerate Hubbard models. Our results ascribe the overall low-frequency spectrum of LMO to charge-transfer mechanisms involving the t2g and eg electrons of the Mn ions, without invoking the presence of excitonic contributions. This finding definitely promotes a Mott-Hubbard scenario for LMO and provides an estimate of the Hamiltonian parameters.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2011