Eur. Phys. J. B 14, 617-625 (2000)
https://doi.org/10.1007/s100510051070

Temperature dependence of infrared conductivity of manganites Pr_0.7Ca_0.3-xSr_xMnO₃ (x = 0, 0.05 and 0.2)

¹ Laboratoire d'Électrodynamique des Matériaux AvancésLRC M01 associated to Commissariat à l'Énergie Atomique, FRE 2077 associated to CNRS, Faculté des Sciences & Techniques, Université François Rabelais, 37200 Tours, France
² CRISMATUMR 6508, ISMRA, boulevard Maréchal Juin, 14050 Caen, France

Received: 20 July 1999
Revised: 15 October 1999
Published online: 15 April 2000

Abstract

The temperature dependence of the reflectivity spectra of three manganites ceramics with compositions Pr_0.7Ca_0.3MnO₃, Pr_0.7Ca_0.25Sr_0.05MnO₃ and Pr_0.7Ca_0.1Sr_0.2MnO₃ has been investigated by infrared reflectivity spectroscopy in the wave number range 0.005-1.1 eV. The compound Pr_0.7Ca_0.25Sr_0.05MnO₃ which shows the largest conductivity jump at the ferromagnetic-paramagnetic phase transition has been studied in details. The optical conductivity of this compound is deduced from the best fit to reflectivity spectra of a "double-damping Drude" model, itself derived from the factorized form of the dielectric function. Excellent agreement with Kramers-Kronig transformation is reported. The model allows in particular to discriminate the contributions to the optical conductivity of trapped charges (polarons) and mobile charge carriers.