Magnetism and Structural Distortion in the La0.7Sr0.3MnO3 Metallic Ferromagnet

TL;DR

This study uses neutron scattering to analyze the spin and lattice dynamics of La0.7Sr0.3MnO3, revealing large spin wave stiffness, typical metallic ferromagnet behavior, and structural details including oxygen octahedra rotations.

Contribution

It provides detailed insights into the spin and lattice dynamics of La0.7Sr0.3MnO3, highlighting the large spin wave stiffness and structural stability across the magnetic transition.

Findings

Large spin wave stiffness constant indicating high electron transfer energy.

Behavior similar to other metallic ferromagnets like Fe or Ni.

Structural distortion from oxygen octahedra rotations with no primary lattice distortion anomaly at Tc.

Abstract

Neutron scattering studies on a single crystal of the highly-correlated electron system, La1-xSrxMnO3 with x~0.3, have been carried out elucidating both the spin and lattice dynamics of this metallic ferromagnet. We report a large measured value of the spin wave stiffness constant, which directly shows that the electron transfer energy of the d band is large. The spin dynamics, including magnetic critical scattering, demonstrate that this material behaves similar to other typical metallic ferromagnets such as Fe or Ni. The crystal structure is rhombohedral, as previously reported, for all temperatures studied (below ~425K). We have observed new superlattice peaks which show that the primary rhombohedral lattice distortion arises from oxygen octahedra rotations resulting in an R-3c structure. The superlattice reflection intensities which are very sensitive to structural changes are independent of temperature demonstrating that there is no primary lattice distortion anomaly at the magnetic transition temperature, Tc = 378.1 K, however there is a lattice contraction.