Structural, thermal, transport, and magnetic properties of the charge-orderedLa1/3Ca2/3MnO3oxide

Abstract

The compound ${\mathrm{La}}_{1/3}{\mathrm{Ca}}_{2/3}{\mathrm{MnO}}_3$ has been studied in the temperature range from 1.5 to 400 K. The anomalous behavior of the resistivity, magnetic susceptibility, specific heat, and lattice parameters are the signature of a charge-ordering transition taking place at around 270 K. A structural model of this charge-ordered state is developed with a crystallographic unit cell given by $(3a\times b\times c)$ of the high-temperature unit cell and the same Pbnm symmetry. At 170 K an antiferromagnetic transition is clearly established on the magnetic susceptibility, resistivity, and specific heat. Neutron diffraction shows that the Mn magnetic moments order antiferromagnetically with a propagation vector $\mathbf{k}=(0,1/2,0).$ The observed magnetic configuration belongs to one of the two bidimensional representations of the group Pbnm associated with $\mathbf{k}=(0,1/2,0).$