Paramagnetic spin correlations in colossal magnetoresistive La0.7Ca0.3MnO3

Abstract

Neutron spectroscopy measurements reveal dynamic spin correlations throughout the Brillouin zone in the colossal magnetoresistive system La0.7Ca0.3MnO3 at 265 K (1.03 TC). The longwavelength behavior is consistent with spin diffusion, yet an additional and unexpected component of the scattering is also observed in low-energy constant-E measurements which takes the form of ridges of strong scattering running along (H 0 0) and equivalent directions. Well defined Q-space correlations are observed in constant-E scans at energies up to at least 28 meV, suggesting robust short-range spin correlations in the paramagnetic phase.