Condensed Matter Theory Seminar: Ajesh Kumar, University of Texas Austin, “Moiré simulation of phases beyond the Landau paradigm”

Landau’s theory of phase transitions and Fermi liquid theory have been foundational developments in describing phases and phase transitions. Experimental and theoretical progress of recent decades, however, have pointed out the necessity of thinking beyond the Landau paradigm. Examples include non-Fermi liquid behavior due to the coupling of a Fermi surface to a gapless collective bosonic mode, and continuous quantum phase transitions corresponding to a discontinuous jump of the Fermi volume, both of which widely occur in strongly correlated electronic systems such as the high-temperature superconductors and heavy-fermion compounds. The strongly coupled nature of these problems and the limited experimental tunability makes understanding their properties very challenging.
In this talk, I will describe how moiré materials, having remarkable tunability and simple microscopic descriptions, can enable progress on these long-standing problems. I will present a trilayer transition metal dichalcogenide moiré heterostructure that can tune across a heavy-fermion quantum critical point, where the Fermi volume jumps discontinuously, and twisted bilayer graphene in a magnetic field as a promising platform to realize and study the problem of a Fermi surface coupled to a fluctuating gauge field.
Host: Meng Cheng (m.cheng@yale.edu)
Please email Taylor Dunnigan (taylor.dunnigan@yale.edu) for zoom information.