Lattice Effects and Magnetic Order in the Canted Ferromagnetic InsulatorLa0.875Sr0.125MnO3+δ

The structural, magnetic, and transport behavior of orthorhombic, insulating La{sub 0.875}Sr{sub 0.125}MnO{sub 3+{delta}} were studied as a function of temperature from 20 to 300 K. Upon cooling from room temperature, we observe the rapid development of a large breathing-mode distortion coincident with large positive and negative thermal expansions for the {ital c} and {ital b} axes, respectively. The onset of canted ferromagnetic ordering at 220 K is correlated with the relaxation of this distortion, which reaches values similar to those at room temperature when the magnetic ordering saturates. We observe no first-order-type discontinuity in the volume at the ferromagnetic transition. These results demonstrate a strong coupling between magnetic ordering and crystal structure even though there is no metal-insulator transition associated with the magnetic transition. {copyright} {ital 1996 The American Physical Society.}