Structural, thermal, transport, and magnetic properties of the charge-ordered La1/3Ca2/3MnO3 oxide

The compound La1/3Ca2/3MnO3 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 (3axbxc) 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 k=(0,1/2,0). The observed magnetic configuration belongs to one of the two bidimensional representations of the group Pbnm associated with k= (0,1/2,0). [S0163-1829(99)02902-1].