title: On the energy scale involved in the metal to insulator transition of quadruple perovskite EuCu3Fe4O12: infrared spectroscopy and ab-initio calculations.
abstract: Optical measurements were carried out by infrared spectroscopy on AA'3B4O12 A-site ordered quadruple perovskite EuCu3Fe4O12 (microscopic sample) as function of temperature. At 240 K (=TMI), EuCu3Fe4O12 undergoes a very abrupt metal to insulator transition, a paramagnetic to antiferromagnetic transition and an isostructural transformation with an abrupt large volume expansion. Above TMI, optical conductivity reveals a bad metal behavior and below TMI, an insulating phase with an optical gap of 125 meV is observed. As temperature is decreased, a large and abrupt spectral weight transfer toward an energy scale larger than 1 eV is detected. Concurrently, electronic structure calculations for both high and low temperature phases were compared to the optical conductivity results giving a precise pattern of the transition. Density of states and computed optical conductivity analysis identified Cu3dxy, Fe3d and O2p orbitals as principal actors of the spectral weight transfer. The present work constitutes a first step to shed light on EuCu3Fe4O12 electronic properties with optical measurements and ab-initio calculations.
authors.affiliation: GREMAN, CNRS UMR 7347-CEA, Université F. Rabelais, UFR Sciences, Parc de Grandmont, Tours, 37200, France.
authors.forename: B
authors.initials: B
authors.lastname: Brière
authors.affiliation: Synchrotron Soleil, Université Paris-Saclay, L'Orme des Merisiers, 91190 Saint-Aubin, France.
authors.forename: A
authors.initials: A
authors.lastname: Kalinko
authors.affiliation: Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, Sakai, Osaka Japan.
authors.forename: I
authors.initials: I
authors.lastname: Yamada
authors.affiliation: Synchrotron Soleil, Université Paris-Saclay, L'Orme des Merisiers, 91190 Saint-Aubin, France.
authors.forename: P
authors.initials: P
authors.lastname: Roy
authors.affiliation: Synchrotron Soleil, Université Paris-Saclay, L'Orme des Merisiers, 91190 Saint-Aubin, France.
authors.forename: J B
authors.initials: JB
authors.lastname: Brubach
authors.affiliation: GREMAN, CNRS UMR 7347-CEA, Université F. Rabelais, UFR Sciences, Parc de Grandmont, Tours, 37200, France.
authors.forename: R
authors.initials: R
authors.lastname: Sopracase
authors.affiliation: GREMAN, CNRS UMR 7347-CEA, Université F. Rabelais, UFR Sciences, Parc de Grandmont, Tours, 37200, France.
authors.forename: M
authors.initials: M
authors.lastname: Zaghrioui
authors.affiliation: GREMAN, CNRS UMR 7347-CEA, Université F. Rabelais, UFR Sciences, Parc de Grandmont, Tours, 37200, France.
authors.forename: V Ta
authors.initials: VT
authors.lastname: Phuoc