Dresden 2017 – wissenschaftliches Programm
MA 44.6: Vortrag
Mittwoch, 22. März 2017, 16:30–16:45, HSZ 403
Pseudo-Goldstone magnons in the Heisenberg helimagnet ZnCr2Se4. — •Yuliia Tymoshenko1, Yevhen Onykiienko1, Pavlo Portnichenko1, Alistair Cameron1, Doug Abernathy2, Jacques Ollivier3, Astrid Schneidewind4, Vladimir Tsurkan5, and Dmytro Inosov1 — 1TU Dresden, D-01069 Dresden, Germany — 2ORNL, Oak Ridge, Tennessee 37831, USA — 3ILL, 38042 Grenoble, France — 4JCNS, D-85747 Garching, Germany — 5University of Augsburg, 86135 Augsburg, Germany
Chromium spinels provide great opportunities to investigate magnetic interactions between classical spins on the almost ideal pyrochlore lattice. ZnCr2Se4 is a spinel compound with incommensurate spin-spiral ground state. In this talk we present inelastic neutron scattering measurements of magnetic excitations in ZnCr2Se4 over a wide range of energies in the whole Brillouin zone. Comparing our data with spin-dynamical calculations we have extracted exchange parameters up to the fourth nearest neighbour and found a good agreement with the isotropic Heisenberg model. Furthermore, measurements of low-energy helimagnon excitations performed in the single-domain spin spiral state revealed two distinct modes: the Goldstone mode emerging from incommensurate magnetic Bragg peaks and a soft pseudo-Goldstone mode emanating from an orthogonal wave vector.