Physical Society Colloquium
Symmetry protected Luttinger liquids on the surface of
Quantum Hall Nematics
Department of Physics
McGill University
Quantum Hall Ferromagnets are a unique platform for studying the confluence
of two pillars of condensed matter physics - symmetry-breaking phenomena,
and topological physics. The consequence of this is a rich phenomenology of
ground states and excitations which derive their properties from both these
pillars. In this talk, I will describe a class of quantum Hall ferromagnets
that have been observed very recently on the surface of Bi(111) by Feldman et
al. [1]. These are different from previously explored quantum
Hall ferromagnets both theoretically in that they arise in multi-valley
systems and ferromagnetism occurs by the spontaneous breaking of symmetry
between these valleys. More recent STM experiments [2]
directly probe the excitations residing between ferromagnetic domains of
opposite polarization. Curiously, domain walls appear to host low energy
excitations that are gapped/gapless depending upon the filling fraction of
the quantum Hall states. I will discuss how we explain [3]
these observations both qualitatively and quantitatively, and highlight the
crucial role of interactions and symmetries specific to multi-valley systems
in engendering such excitations.
[1] B. Feldman et al., Science 2016
[2] M. T. Randeria, K. Agarwal et al., Nature 566
(2019)
[3] K. Agarwal et al., Phys Rev. B 100, 165103
(2019)
Friday, February 28th 2020, 15:30
Ernest Rutherford Physics Building, Keys Auditorium (room 112)
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