title: Upward renormalization of fluctuations in CsMnBr3 with increasing temperature.
abstract: The temperature dependence of the spin-wave gap in the triangular antiferromagnet CsMnBr3 was studied above the three-dimensional ordering temperature T(N)=8.3 K along the main symmetry directions using inelastic neutron scattering. We find at T(N) two gapped dispersive modes, whose energy increases with temperature. Moreover, the width of the spin-wave band along the [110] direction increases also. In a second session, polarization analysis was applied in order to extract explicitly the components with in-plane and out-of-plane character. The results show that both gapped modes (with axial and radial symmetry) renormalize upwards with rising temperature. We show that this behavior is not compatible with spin-wave theory. In addition, we find a new magnetic anomaly in the paramagnetic phase.
authors: Physik-Department E21, Technische Universität Munich, D-85747 Garching, Germany.
authors: C
authors: C
authors: Reich
authors: P
authors: P
authors: Böni
authors: B
authors: B
authors: Roessli
authors: E
authors: E
authors: Rastelli