Regensburg 2013 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 45: Magnetic Coupling and Spin Structures
MA 45.14: Vortrag
Donnerstag, 14. März 2013, 18:30–18:45, H10
Fictitious excitations in the classical Heisenberg antiferromagnet on the kagome lattice — •Stefan Schnabel1 and David P. Landau2 — 1Universität Leipzig — 2University of Georgia, USA
In the last decades the classical Heisenberg antiferromagnet on the kagome lattice has been subject of a number of theoretical and numerical studies and today its behavior is widely understood. A prominent feature is ‘ordering by disorder’ meaning the entropy-driven formation of a highly degenerate coplanar state at low temperature. There remain, however, a few open questions. For the coplanar regime analytical investigations predict an acoustic branch of spin waves, while a recent numerical study [1] using standard spin dynamics techniques suggests the existences of additional optical modes. We show how this discrepancy arises from different descriptions of the system and demonstrate that the structure of the low-temperature state causes shifts in Fourier space, thus creating a fictitious optical branch. Furthermore, we applied an advanced Monte Carlo method in combination with spin dynamics simulations of high precision and found very good agreement with the theoretical results regarding the dynamic behavior at low temperatures.
[1] J. Robert, B. Canals, V. Simonet, and R. Ballou, Phys. Rev. Lett. 101, 117207 (2008).
[2] S. Schnabel and D. P. Landau, Phys. Rev. B 86, 014413 (2012).