Inelastic neutron scattering study of spin waves in the garnet with a triangular magnetic structure

Abstract

The spin-wave spectrum of the antiferromagnet with the garnet structure has been studied by inelastic neutron scattering on the triple-axis spectrometers IN12 and IN14 at ILL. Magnon dispersion curves were measured along and directions up to energies of 0.3 THz. The spin-wave symmetry analysis, which reduced the number of independent exchange parameters to six, was performed to ensure correct description of the spin-wave branches. As determined by the fitting, five of the parameters are statistically significant and have been found to be , and . This quite unusual sequence of exchange parameters clearly demonstrates the importance of the superexchange chain geometry.