Abstract: Strongly correlated electron systems typically exhibit bad-metal behavior, which is operationally defined in terms of a resistivity at room temperature that exceeds the Mott-Ioffe-Regel limit. These systems show a rich landscape of electronic orders. Exploring this landscape is an important means to clarify the underlying microscopic physics.
Iron-based superconductors present a striking case study. They are well established to be bad metals, and their various types of electronic orders are essentially always accompanied by nematicity. In this talk, I will address the nematic aspect of this decade-old subject and summarize the effort towards a unified description of these electronic orders. A particular emphasis will be on recent studies for the intermediate-strength regime of electron correlations, including Hund’s couplings, using a variational Monte Carlo method. Implications of these results 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 recent theoretical study which demonstrates such nematicity in a ``fragile insulator”, predicts its persistence in the bad metal regime and provides a new perspective on the overall phase diagram of these systems.
Biography: Qimiao Si is the Harry C. and Olga K. Wiess Professor of Physics at Rice University and Director of Rice Center for Quantum Materials. Prior to joining Rice in 1994, he obtained a Ph.D. degree from the University of Chicago in 1991 and was a postdoctoral fellow at Rutgers University and University of Illinois at Urbana-Champaign. His major contributions have been on the theory of strongly correlated electron systems, including quantum criticality, high temperature iron-based superconductivity, and strongly correlated electronic topology. He was elected to Fellow of the American Association for the Advancement of Science, American Physical Society, and the British Institute of Physics, received a Humboldt Research Award and was selected as the 2019 Ulam Distinguished Scholar at the Los Alamos National Laboratory. He serves as a General Member on the Board of the Aspen Center for Physics.
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2020-09-24T14:00:002020-09-24T15:00:00CM seminar - Bad Metals and Electronic Orders – Nematicity from Iron Pnictides to Moiré SystemsEvent Information:
Abstract: Strongly correlated electron systems typically exhibit bad-metal behavior, which is operationally defined in terms of a resistivity at room temperature that exceeds the Mott-Ioffe-Regel limit. These systems show a rich landscape of electronic orders. Exploring this landscape is an important means to clarify the underlying microscopic physics.
Iron-based superconductors present a striking case study. They are well established to be bad metals, and their various types of electronic orders are essentially always accompanied by nematicity. In this talk, I will address the nematic aspect of this decade-old subject and summarize the effort towards a unified description of these electronic orders. A particular emphasis will be on recent studies for the intermediate-strength regime of electron correlations, including Hund’s couplings, using a variational Monte Carlo method. Implications of these results 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 recent theoretical study which demonstrates such nematicity in a ``fragile insulator”, predicts its persistence in the bad metal regime and provides a new perspective on the overall phase diagram of these systems.
Biography: Qimiao Si is the Harry C. and Olga K. Wiess Professor of Physics at Rice University and Director of Rice Center for Quantum Materials. Prior to joining Rice in 1994, he obtained a Ph.D. degree from the University of Chicago in 1991 and was a postdoctoral fellow at Rutgers University and University of Illinois at Urbana-Champaign. His major contributions have been on the theory of strongly correlated electron systems, including quantum criticality, high temperature iron-based superconductivity, and strongly correlated electronic topology. He was elected to Fellow of the American Association for the Advancement of Science, American Physical Society, and the British Institute of Physics, received a Humboldt Research Award and was selected as the 2019 Ulam Distinguished Scholar at the Los Alamos National Laboratory. He serves as a General Member on the Board of the Aspen Center for Physics.Event Location:
Zoom - TBA