Unusual large magnetostriction in the ferrimagnet Gd_2/3Ca_1/3MnO₃

Centro Atómico Bariloche (CNEA) and Instituto Balseiro (U. N. Cuyo) - 8400 Bariloche, Río Negro, Argentina

^a victor.correa@cab.cnea.gov.ar

Received: 2 March 2012
Accepted: 12 April 2012

Abstract

We report an unusual large linear magnetostrictive effect in the ferrimagnet Gd_2/3Ca_1/3MnO₃ (T_c≈80 K). Remarkably, the magnetostriction, negative at high temperature (T≈T_c), becomes positive below 15 K when the magnetization of the Gd sublattice overcomes the magnetization of the Mn sublattice. A rather simple model where the magnetic energy competes against the elastic energy gives a good account of the observed results and confirms that Gd plays a crucial role in this unusual observation. Unlike previous works in manganites where only striction associated with 3d Mn orbitals is considered, our results show that the lanthanide 4f-orbitals–related striction can be very important too and it cannot be disregarded.