Polarised neutron scattering study of magnetic correlations and spin dynamics in La0.875Sr0.125MnO3+δ

The rhombohedral La0.875Sr0.125MnO3+δ compound exhibits colossal magnetoresistance in the vicinity of the ferromagnetic transition, Tc (∼250 K). From neutron polarisation analysis measurements, the scattering peak in the forward direction above Tc (Tc>T>1.6Tc), showed a Lorentzian-type q dependence, with magnetic correlation lengths (Ornstein–Zernike form) in the range 11–14 Å. This forward scattering peak has both neutron spin-flip and non-spin-flip components and our measurements demonstrate that we have simultaneously observed the lattice and magnetic components of polarons above Tc. From the energy scale of the observed diffusive fluctuation in this compound, the polarons were determined to have a mobility of ∼2.5×10-11 cm2 s-1at room temperature.