Spin dynamics of classical kagome antiferromagnets

Datum

31.03.2011

Zeit

14:00 - 15:15

Sprecher

Mathieu Taillefumier

Zugehörigkeit

Trondheim - Norway

Sprache

en

Hauptthema

Physik

Andere Themen

Physik

Host

Condensed Matter Seminar

Beschreibung

By combining monte carlo and spin dynamics simulations, we investigate the possibility of coherent excitations in classical kagome antiferromagnets through the calculation of the dynamical structure factors $S(Q, \omega)$ (resp. the powder averaged $S(|Q|, \omega)$). In the dense, non disordered case, evidences for spin wave like excitations are given: we show that the Heisenberg kagome antiferromagnet has two distincts low temperature dynamical regimes, whose temperature ranges are given by the entropically driven onset of spin plane coplanarity at T /J 5 × 10−3 . We furthermore show that the low temperature manifold is very fragile and that the spin dynamics strongly depends on the ratio of disorder, whatever its type (non-magnetic impurities or bond distortions). Antisymmetric interactions are finally taken into account as another source of perturbation.

Letztmalig verändert: 31.03.2011, 09:35:21