Eur. Phys. J. B 66, 301-305 (2008)
https://doi.org/10.1140/epjb/e2008-00441-1

High pressure Raman study of La_1-xCa_xMnO_3-δ manganites

¹ Laboratorium für Festkörperphysik, ETH-Zürich, 8093 Zürich, Switzerland
² Dipartimento di Fisica Università di “Roma Tre”, Via della Vasca Navale 84, 00146 Roma, Italy
³ “Coherentia” CNR-INFM and Dipartimento di Fisica, Università di Roma “La Sapienza”, Piazzale Aldo Moro 2, 00185 Roma, Italy

Corresponding author: ^a sacchetti@phys.ethz.ch

Received: 18 June 2008
Revised: 16 September 2008
Published online: 4 December 2008

Abstract

We report a high-pressure Raman study on two members of the La_1-xCa_xMnO_3-δ manganite family (x = 0.20, δ = 0 and δ = 0.08). The results obtained for the δ = 0 sample show a different behavior in the low and high pressure regime which is ascribed to the onset of a new pressure-activated interaction previously invoked in other manganite compounds. The comparison of our results with literature data gives further support to the identification of the Jahn-Teller sensitive stretching mode and shows that pressure-induced octahedral symmetrization is more effective in systems exhibiting a lower metallic character. On the contrary the new interaction sets in at a pressure which decreases on increasing the metallic character of the system indicating an important role of the Mn–Mn hopping integral in its activation.