Inelastic neutron scattering study of La2CuO4

The phonon dispersion curves as well as high energy magnetic excitations in La2CuO4 were investigated by inelastic neutron scattering on a large single crystal (V ∼ 0.8 cm3). A few low energy phonon branches were determined at the Kurchatox Institute in Moscow, whereas the main part of the experiments was carried out at Saclay. The magnetic excitations were studied up to E + 76.5 meV at 18 K and 295 K. They were found to exhibit a linear dispersion of 0.89 eV · Angstrom. Nearly all phonon branches were determined in the main symmetry directions (100), (110) and (001) (in tetragonal notation). Most measurements were done at room temperature but additional measurements were performed above the structural phase transition (495 K) to explore the influence of the tilting of the octahedra on the lattice dynamics