Seminars
Quantum Criticality in Twisted Transition Metal Dichalcogenides








April 21st, 2021 ABHAY PASUPATHY Columbia University

In moiré heterostructures, gate-tunable insulating phases driven by electronic correlations have been recently discovered. Here, we use transport measurements to characterize the gate-driven metal-insulator transitions and the metallic phase in twisted WSe2 near half filling of the first moiré subband. We find that the metal-insulator transition as a function of both density and displacement field is continuous. At the metal-insulator boundary, the resistivity displays strange metal behaviour at low temperature with dissipation comparable to the Planckian limit. Further into the metallic phase, Fermi-liquid behaviour is recovered at low temperature which evolves into a quantum critical fan at intermediate temperatures before eventually reaching an anomalous saturated regime near room temperature. An analysis of the residual resistivity indicates the presence of strong quantum fluctuations in the insulating phase. These results establish twisted WSe2 as a new platform to study doping and bandwidth controlled metal-insulator quantum phase transitions on the triangular lattice.

Bio:
Abhay Pasupathy is a Professor of Physics at Columbia University and a Group Leader in the Condensed Matter Physics Department at Brookhaven National Laboratory. His group is interested in understanding the electronic properties of quantum materials. Currently much of the research in the group is centered around two-dimensional materials and their heterostructures. The typical experimental techniques used are scan probe microscopy and electronic transport measurements.

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L4G Seminar, April 21, 2021, 15:00. Online (Zoom))

Hosted by Prof Adrian Bachtold


This activity is co-funded by the European Regional Development Funds (ERDF) allocated to the Programa operatiu FEDER de Catalunya 2014-2020, with the support of the Secretaria d’Universitats i Recerca of the Departament d’Empresa i Coneixement of the Generalitat de Catalunya for emerging technology clusters devoted to the valorization and transfer of research results (GraphCAT 001-P-001702).

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