The local structure about the Mn site in the half-doped system La 1/2Ca1/2MnO3 was measured in magnetic fields up 10 T to probe the melting of the charge-ordered state. Examination of the Mn-O and Mn-Mn correlations reveals three distinct regions in the structure-field diagram. A broad region with weak field dependence (mainly antiferromagnetic phase below 7.5 T), a narrow-mixed phase region near ∼8.5 T and a high-field ferromagnetic phase region with strong field-structure coupling are found. At high field the Mn-O radial distribution becomes Gaussian and the Mn-Mn correlations are enhanced-consistent with the dominance of a ferromagnetic phase. Comparison of the structural measurements with transport and magnetization measurements suggests that the exponential changes in resistivity in the first region are dominated by the reordering of the moments on the Mn sites from CE type antiferromagnetic to ferromagnetic order with only a weak change in the local distortions of the MnO6 octahedra.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jul 2004|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics