CMSA Strongly Correlated Quantum Materials and High-Temperature Superconductors Series: Bad Metals and Electronic Orders – Nematicity from Iron Pnictides to Graphene Moiré Systems

CMSA EVENTS

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November 25, 2020 10:30 am - 12:00 pm
via Zoom Video Conferencing
Speaker:

Qimiao Si - Rice University

Strongly correlated electron systems often show bad-metal behavior, as operationally specified in terms of a resistivity at room temperature that reaches or exceeds the Mott-Ioffe-Regel limit. They display a rich landscape of electronic orders, which provide clues to the underlying microscopic physics. Iron-based superconductors present a striking case study, and have been the subject of extensive efforts during the past decade or so. They are well established to be bad metals, and their phase diagrams prominently feature various types of electronic orders that are essentially always accompanied by nematicity. In this talk, I will summarize these characteristic features and discuss our own efforts towards understanding the normal state through the lens of the electronic orders and their fluctuations. Implications for superconductivity will be briefly discussed. In the second part of the talk, I will consider the nematic correlations that have been observed in the graphene-based moiré narrow-band systems. I will present a theoretical study which demonstrates nematicity in a “fragile insulator”, predicts its persistence in the bad metal regime and provides an overall perspective on the phase diagram of these correlated systems.

Zoom: https://harvard.zoom.us/j/977347126