IMX Seminar Series - Novel thermal probes of the many-body states in magic angle twisted bilayer graphene

Twist-angle engineering of 2D materials has led to the recent discoveries of novel many-body ground states in moiré systems such as correlated insulators, unconventional superconductivity, strange metals, orbital magnetism and topologically nontrivial phases. These systems are clean and tuneable, where all phases can coexist in a single device, which opens up enormous possibilities to address key questions about the nature of correlation induced superconductivity and topology, and allows to create entirely novel quantum phases with enhanced interactions. In this talk we will introduce some of the main concepts underlying these systems, concentrating on magic angle twisted bilayer graphene (MATBG) and show how symmetry-broken states emerge at all integer electron fillings [1]. We further will discuss recent experiments including screened interactions [2], Chern insulators [3], magnetic Josephson junctions [4], quantum criticality [5], re-entrant correlated insulators at high magnetic fields [6], Dirac spectroscopy of correlated states in magic angle trilayers and discuss some of the avenues for novel quantum sensing applications [8].
[1] Nature, 574, 653 (2019).
[2] Nature, 583, 375–378 (2020).
[3] Nature Physics, 17, 710 (2021).
[4] arXiv:2110.01067 (2021).
[5] Nature Physics, 18, 633 (2022).
[6] PRL 128, 217701 (2022).
[7] Nature Materials, in press (2022).
[8] Nano Letters, 22, 6465(2022).

Bio: Prof. Dr. Dmitri K. Efetov (M) received a Diploma (M.Sc.) in Physics from ETH Zurich (CH) in 2007. Subsequently Dmitri earned a M.A., M. Ph. and Ph.D. in Physics from Columbia University (USA) in 2014, under the supervision of one of the pioneers of graphene Prof. Dr. Philip Kim, with a thesis titled “Towards inducing superconductivity into graphene”. Dmitri then worked as a Postdoctoral Researcher at the Massachusetts Institute of Technology (MIT, USA) in the group of Prof. Dr. Dirk Englund, developing ultra-fast microwave thermometry and single photon detectors based on graphene. Since 2017 Dmitri was an Assistant Professor and Group Leader at ICFO (SP), and since 2021 is a Full Professor (W3) and Chair of Solid State Physics at LMU Munich (GER), with a research program that concentrates on the investigation of novel “moiré materials” at the intersection of condensed matter physics, optics and quantum science. Prof. Efetov received the Charles H. Towns Award for his outstanding research achievements during his PhD, the Obra Social ”laCaixa” Junior Leader Fellowship, an ERC Starting Grant, was a finalist of the LaVanguardia Science Prize, received the 2022 IUPAP Early Career Scientist Prize in Semiconductor Physics, and won the DFG Leibniz prize 2024 for his improvement of the device quality and the ground-breaking fundamental investigations of novel insulating, superconducting and topological phases in magic angle twisted bilayer graphene. He was the leader of the 2D-SIPC project in the EUs Quantum Technology Flagship, as well as a member of its Science and Engineering board. He is now a core-member of the Munich Center of Quantum Science and Technology (MCQST) and is member of the advisory board of the Center of Nano Science (CeNS).