Magnetostriction and thermal expansion anomalies near the Curie point of the compound La0.7Sr0.3MnO3 with the perovskite structure

It is found that the bulk part omega of the magnetostriction near the Curie temperature T-c in a La0.7Sr0.3MnO3 single crystal with the perovskite structure is negative and that the temperature dependence of /omega/ has a maximum near T-c. The quantity /omega/ at the maximum increases rapidly with increasing magnetic field. The thermal expansion coefficient near T-c increases with temperature much Easter than linearly. The paramagnetic Curie temperature determined from the Curie-Weiss law, which the paramagnetic susceptibility of this crystal satifies, was found to be lower than T-c. These anomalies and also the near-T-c metal-insulator transition which is characteristic for this material are explained by the existence of a magnetically two-phase state consisting of a conducting ferromagnetic matrix containing antiferromagnetic insulating microregions occupying not more than 5% of the sample volume. (C) 1997 American Institute of Physics.