https://doi.org/10.1140/epjb/e2002-00157-2
Quantum spin dynamics of the bilayer ferromagnet La1.2Sr1.8Mn2O7
1
Max–Planck–Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany
2
Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France
3
Institut für Theoretische Physik III, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
4
Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, 01187 Dresden, Germany
Corresponding author: a shannon@mpipks-dresden.mpg.de
Received:
15
January
2002
Published online:
6
June
2002
We construct a theory of spin wave excitations in the bilayer manganite La1.2Sr1.8Mn2O7 based on the simplest possible double–exchange model, but including leading quantum corrections to the spin wave dispersion and damping. Comparison is made with recent inelastic neutron scattering experiments. We find that quantum effects account for some part of the measured damping of spin waves, but cannot by themselves explain the observed softening of spin waves at the zone boundary. Furthermore a doping dependence of the total spin wave dispersion and the optical spin wave gap is predicted.
PACS: 75.30.DS – Spin waves / 75.25.+z – Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source X-ray scattering, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2002