Neutron scattering and magnetization studies of the spin correlations on the kagomé lattice antiferromagnet KFe₃(Oh)₆(SO₄)₂

(cont.) The former represents a continuous planar rotational symmetry corresponding to the SO(2) symmetry, while the latter is a discrete symmetry associated with the Z2 symmetry. Depending on which measurements are performed, the critical behavior of the system can belong to either SO(2) or Z2 universality classes with two distinct critical temperatures; one is associated with the spontaneous breaking of the Z2 symmetry, and the other corresponds to a topological order (BKT transition) due to vortex- antivortex binding. The former occurs at a slightly higher temperature than the latter. Neutron scattering measurements show a signature of the BKT transition, while specific heat measurements show a feature of the 2D Ising transition. Above TN, the in-plane spin gap vanishes, and the system retains the SO(2) symmetry when measured with neutron scattering. On the other hand, specific heat measurements show a feature of the 2D Ising transition, since the underlying symmetry of the spin Hamiltonian is the time-reversal or Z2 symmetry.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Matan, Kittiwit

Advisor dc:contributor.advisor

• Young S. Lee.

• Physics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/45433

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/45433