THE FIRST OBSERVATION OF DYNAMICAL CHIRALITY BY MEANS OF POLARIZED NEUTRON-SCATTERING IN THE TRIANGULAR LATTICE ANTIFERROMAGNET CSMNBR3

The polarization-dependent part of the neutron scattering in the trian gular-lattice antiferromagnet CsMnBr3 is studied. This scattering appe ars in an external magnetic field and is determined by the projection of a chiral fluctuation on the sample magnetization (the dynamical chi rality, DC). It is shown that the DC cross section is an odd function of the energy transfer, omega, and is proportional to the magnetic fie ld up to LO kOe above T-N. A Be filter is used instead of the analyser for measuring the DC scattering integrated over omega < 0. It is show n that below T-N the field dependence of this intensity reveals two fe atures related to the acoustic spin waves and to a new type of low-ene rgy magnetic excitation, presumably of topological nature. The tempera ture dependence of the acoustic spin waves near T-N is in qualitative agreement with dynamical scaling.