Monday, June 11, 2012

1206.1795 (S. Toth et al.)

Magnetic soft modes in the locally distorted triangular antiferromagnet
alpha-CaCr2O4
   [PDF]

S. Toth, B. Lake, K Hradil, T. Guidi, K. C. Rule, M. B. Stone, A. T. M. N. Islam
In this paper we explore the phase diagram and excitations of a distorted triangular lattice antiferromagnet. The unique two-dimensional distortion considered here is very di?erent from the 'isosceles'-type distortion that has been extensively investigated. We show that it is able to stabilize a 120{\deg} spin structure for a large range of exchange interaction values, while new structures are found for extreme distortions. A physical realization of this model is \alpha-CaCr2O4 which has 120{\deg} structure but lies very close to the phase boundary. This is veri?ed by inelastic neutron scattering which reveals unusual roton-like minima at reciprocal space points di?erent from those corresponding to the magnetic order.
View original: http://arxiv.org/abs/1206.1795

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