Dresden 2006 – wissenschaftliches Programm
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MA: Magnetismus
MA 5: Spin-Structures and Magnetic Phase Transitions I
MA 5.5: Vortrag
Montag, 27. März 2006, 11:15–11:30, HSZ 403
Complex Magnetic Ordering Process in the Frustrated A-Site Thiospinel MnSc2S4 — •M. Mücksch1,2, A. Krimmel1, A. Podlesnyak3, D. Sheptyakov3, A. Cervellino3, V. Tsurkan1,4, C. Ritter2, M.M. Koza2, H. Mutka2, S. Horn1, and A. Loidl1 — 1Institut für Physik, Universität Augsburg, D-86159 Augsburg, Germany — 2Institut Laue-Langevin, BP 156 X, F-38042 Grenoble, France — 3Laboratory for Neutron Scattering, ETHZ & PSI, CH-5232 Villigen PSI, Switzerland — 4Institute of Applied Physics, Academy of Sciences of Moldova, MD-2028 Chisinau, Moldova
Extensive neutron scattering experiments have been performed to study the frustration effects in the magnetic A-site sulphur spinel compound MnSc2S4. Starting from the paramagnetic state above 23K a crossover to a fluctuating spin liquid phase is observed for T ≤ 23K≈ |θCW|. Approaching the magnetic ordering temperature at TN2 = 2.3 K we discovered a broad double peak structure of the magnetic intensity around Q-positions corresponding to the (0.75, 0.75, 0) and (1, 0, 0) reciprocal lattice positions, respectively. On further cooling, for 1.9 K=TN1 ≤ T ≤ TN2=2.3 K the peak at (0.75, 0.75, 0) sharpens and becomes dominant in intensity, whereas the intensity centered around (1, 0, 0) remains broad before completely vanishing at TN1=1.9 K. This behaviour can be interpreted as a lock-in transition from an incommensurate to a commensurate structure with decreasing temperature at TN1. The ground state magnetic structure of MnSc2S4 is a cycloid within the (a,b)-plane characterised by a propagation vector q ≈ (0.75, 0.75, 0). Below TN1 well defined dispersive spin-wave excitations emerge.