Quantum Hall Valley Nematics

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• Sid Parameswaran (Oxford)
• Thursday 16 November 2017, 13:45-15:00
• Theory Library.

If you have a question about this talk, please contact Mike Gunn.

The interplay between quantum Hall ordering and spontaneously broken ’’internal’’ symmetries in two-dimensional electron systems with spin or pseudospin degrees of freedom gives rise to a variety of interesting phenomena, including novel phases, phase transitions, and topological excitations.

I will discuss a theory of broken-symmetry quantum Hall states, applicable to a class of multivalley systems, where the symmetry at issue is a point-group element that combines a spatial rotation with a permutation of valley indices. I will explore its ramifications for the phase diagram of a variety of experimental systems, such as AlAs and Si quantum wells and the surface states of bismuth.

I will also discuss unconventional transport phenomena in these phases in the presence of quenched randomness, and the possible mechanisms of selection between degenerate broken-symmetry phases in clean systems.

References: [1] D.A. Abanin, S.A. Parameswaran, S.A. Kivelson and S.L. Sondhi, Phys. Rev. B 82 , 035428 (2010). [2] A. Kumar, S.A. Parameswaran and S.L. Sondhi, Phys. Rev. B 88 , 045133 (2013). [3] A. Kumar, S.A. Parameswaran and S.L. Sondhi, Phys. Rev. B. 93, 014442 (2016).

This talk is part of the Theoretical Physics Seminars series.

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