Paramagnetic Spin Correlations in Colossal Magnetoresistive La$_{0.7}$Ca$_{0.3}$MnO$_{3}$

ORAL

Abstract

Inelastic neutron scattering measurements, taken on the ARCS time-of-flight spectrometer, reveal dynamic spin correlations throughout the Brillouin zone in the colossal magnetoresistive system La$_{0.7}$Ca$_{0.3}$MnO$_{3}$ at 265~K ($\approx$1.03~$T_{C}$). Well defined correlations are observed in constant-$E$ scans. The long-wavelength behavior can be attributed to spin diffusion, qualitatively consistent with dynamical scaling theory, with a correlation length of $\approx$10~{\AA}. Dynamic correlations are observed at energies up to at least 28~meV, suggesting persistent short range spin correlations in the paramagnetic phase. An additional and unexpected component of the scattering is observed at lower energies which takes the form of ridges of strong scattering running along ($H$~0~0) and equivalent directions.

Authors

  • Jeffrey Lynn

    National Institute of Standards and Technology, NCNR, National Institute of Standards and Technology

  • Joel Helton

    NCNR, National Institute of Standards and Technology

  • Matthew Stone

    Oak Ridge National Laboratory

  • Dmitry Shulyatev

    Moscow State Steel and Alloys Institute

  • Dmitry Shulyatev

    Moscow State Steel and Alloys Institute