J Phys Condens Matter. 2012 Feb 22;24(7):076006. doi: 10.1088/0953-8984/24/7/076006. Epub 2012 Feb 01.

The transition from ferromagnet to cluster-glass in La(1-x)Tb(x)Mn1/2Sc1/2O3.

Journal of physics. Condensed matter : an Institute of Physics journal

J Blasco, V Cuartero, J García, J A Rodríguez-Velamazán

PMID: 22293145 DOI: 10.1088/0953-8984/24/7/076006

Abstract

We report the structural and magnetic properties of the La(1-x)Tb(x)Mn(1/2)Sc(1/2)O(3) series. LaMn(1/2)Sc(1/2)O(3) shows a long range ferromagnetic ordering in agreement with a fully polarized Mn-sublattice. The substitution of La with Tb produces structural changes which affect the magnetic properties. This substitution leads to a contraction in the unit cell volume that mainly reduces the M-O-M bond angle (M = Mn, Sc). The bending of this angle decreases the Mn-O-Mn superexchange interaction and enhances the competition between nearest-neighbour and next-nearest-neighbour interactions. Accordingly, the magnetic ground state changes from ferromagnetic to a glassy magnetic state. Large thermal irreversibility between zero-field-cooled and field-cooled conditions is observed for all samples. The study of the dynamic magnetic properties has been performed using the frequency dependent real part of the ac magnetic susceptibility. The use of both the Vogel-Fulcher law and the conventional critical slowing down law yields similarly good accuracies in the fits. The relaxation times obtained from both laws concur with the existence of a cluster-glass for x ≥ 0.5 samples.

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't