Antisite disorder and the magnetic groundstate of an experimental spin 1/2 kagome antiferromagnet

Condensed Matter lunchtime seminar

Antisite disorder and the magnetic groundstate of an experimental spin 1/2 kagome antiferromagnet

  • Event time: 1:00pm
  • Event date: 14th May 2007
  • Speaker: Mark de Vries (University of Edinburgh)
  • Location: Room 2511,

Event details

Physical realisations of the spin 1/2 kagome antiferromagnet have been long sought-after because it is expected that the magnetic groundstate of this system can retain the full symmetry of the magnetic Hamiltonian. I will discuss recent experimental results on Zn_xCu(4-x)(OH)6Cl2 with 0 < x <1. Muon-spin relaxation, neutron diffraction and specific-heat measurements were carried out for a range of stoichiometries up to the x = 1 phase, which has been claimed to be an ideal model of the geometrically frustrated spin 1/2 kagome antiferromagnet. The interpretation of the data is complicated by the presence of antisite disorder between the Cu and the Zn sites, but a detailed analysis of the heat capacity data for compositions 0.5 < x < 1 has allowed for this to be taken into account in the further analysis of the experimental data. I will argue that the effective magnetic Hamiltonian in this narrow-band charge-transfer compound must be of lower symmetry than the Heisenberg Hamiltonian.

This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..

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