University of Birmingham > Talks@bham > Condensed Matter Physics Seminars > New Realisations of Quantum Frustrated Spin Systems from Vanadium Oxyfluorides

New Realisations of Quantum Frustrated Spin Systems from Vanadium Oxyfluorides

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  • UserDr. Lucy Clark, University of Liverpool
  • ClockFriday 29 September 2017, 14:00-15:00
  • HousePhysics East 217.

If you have a question about this talk, please contact Elizabeth Blackburn.

Simple antiferromagnetic exchange interactions on a bipartite lattice lead to well-understood magnetic ground states and elementary magnetic excitations. An enduring theme at the forefront of condensed matter research is the study of frustrated magnets, in which competing magnetic exchange interactions suppress long-range magnetic order and promote new magnetic states of matter. For instance, frustrated spin systems may realise novel quantum-disordered ground states, such as the quantum spin liquid, with fractionalised excitations similar to those observed in one-dimensional magnets [1].

A particularly exciting challenge is the realisation of the quantum kagome antiferromagnet – a highly frustrated network of corner-sharing equilateral triangles of antiferromagnetically interacting S = ½ species. Modelling the exact nature of the ground state of the S = ½ kagome antiferromagnet remains a difficult task, even for the most advanced analytical and numerical methods, due to the rich variety of possible quantum spin liquid phases that compete within a narrow range of energy. A vital means to overcome this problem is to discover and explore more, and different, experimental realisations of the S = ½ kagome antiferromagnet to understand how various perturbations to the ideal Heisenberg Hamiltonian affect the nature of the ground state that is selected [2].

Here, I will present some of our recent work on the chemistry and physics of a new family of inorganic-organic vanadium oxyfluoride compounds [3, 4]. These materials – prepared via an ionothermal synthetic route – uniquely realise an anisotropic, breathing kagome network of S = ½ V4+ cations. They are, therefore, a prime example of how innovative preparative chemistry can help us uncover new and exciting physics. Through magnetisation, heat capacity, muon spin relaxation [5] and solid-state NMR measurements [6], I will show that these new compounds appear to adopt a gapless quantum spin liquid ground state.

References:

[1] L. Balents, Nature 464, 199 (2010).

[2] M. R. Norman, Rev. Mod. Phys. 88, 041002 (2016).

[3] F. H. Aidoudi, D. W. Aldous, R. J. Goff, A. M. Z. Slawin, J. P. Attfield, R. E. Morris and P. Lightfoot, Nature Chem. 3, 801 (2011).

[4] L. Clark, F. H. Aidoudi, C. Black, K. S. A. Arachchige, A. M. Z. Slawin, R. E. Morris and P. Lightfoot, Angewandte Chemie Int. Ed. 54, 15457 (2015).

[5] L. Clark, J. -C. Orain, F. Bert, M. A. de Vries, F. H. Aidoudi, R. E. Morris, P. Lightfoot, J. S. Lord, M. T. F. Telling, P. Bonville, J. P. Attfield, P. Mendels and A. Harrison, Phys. Rev. Lett. 110, 207208 (2013).

[6] J. –C. Orain, B. Bernu, P. Mendels, L. Clark, F. H. Aidoudi, P. Lightfoot, R. E. Morris and F. Bert, Phys. Rev. Lett. 118, 237203 (2017).

This talk is part of the Condensed Matter Physics Seminars series.

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