Happening @ Michigan https://events.umich.edu/group/3811/rss RSS Feed for Happening @ Michigan Events at the University of Michigan. Interdisciplinary QC-CM Seminar | Bridging Hubbard and quantum Hall physics in twisted bilayer graphene (April 4, 2024 4:00pm) https://events.umich.edu/event/120739 120739-21845199@events.umich.edu Event Begins: Thursday, April 4, 2024 4:00pm
Location: West Hall
Organized By: Interdisciplinary QC/CM Seminars

Early on it was noticed that twisted bilayer graphene has elements in common with two paradigmatic examples of strongly correlated physics: Hubbard physics and quantum Hall physics. Indeed, twisted bilayer graphene hosts flat topological bands, but these bands host concentrated charge density, experimental signs of fluctuating magnetism, and signs of unconventional superconductivity. The emergence of fluctuating moments is particularly surprising, as localized Wannier states do not exist in topological bands. I will discuss a model for the twisted bilayer graphene flat bands that centers the concentration of charge density and, relatedly, the concentration of Berry flux. After establishing good quantitative agreement with more microscopic models, I will show how the model hosts parametrically decoupled flavor moments. These flavor moments are tied to Wannier states that are power-law delocalized, with infinite localization length, that nonetheless have parametrically small overlap with each other. I will conclude by discussing some experimental implications for this picture.

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Workshop / Seminar Thu, 28 Mar 2024 07:18:12 -0400 2024-04-04T16:00:00-04:00 2024-04-04T17:00:00-04:00 West Hall Interdisciplinary QC/CM Seminars Workshop / Seminar West Hall
Interdisciplinary QC-CM Seminar | Emergent phases in quantum magnets: fractionalization, fragmentation and new particles (April 11, 2024 4:00pm) https://events.umich.edu/event/120740 120740-21845200@events.umich.edu Event Begins: Thursday, April 11, 2024 4:00pm
Location: West Hall
Organized By: Interdisciplinary QC/CM Seminars

Moire superlattices of van der Waals materials have surfaced as new tunable quantum platforms for the realization of emergent phases. While moire-induced electronic phases have been extensively explored over the past few years, moire engineering of magnetic phases is a newer emerging topic. In the first part of my talk, I will discuss how stacking dependent interlayer exchange can be used to create novel spin textures such as skyrmions. I will illustrate this mechanism by applying it to twisted bilayers of Cr-based trihalides (1) and α-RuCl3 (2). In the second part, I will focus on quantum spin liquid bilayers and discuss how twist angle and interlayer exchange can be utilized to create new topological phases with new emergent quasiparticles such as ‘fractionalized Goldstone bosons’ in these systems (3,4,5).

(1) M. Akram, H. LaBollita, D. Dey, J. Kapeghian, O. Erten, A. Botana Nano Lett. 15, 6633 (2021).
(2) M. Akram, J. Kapeghian, J. Das, R. Valenti, A. Botana, O. Erten Nano Lett. 24, 890 (2024).
(3) E. Nica, M. Akram, A. Vijayvargia, R. Moessner, O. Erten npj Quantum Materials 8, 9 (2023).
(4) A. Vijayvargia, E. Nica, R. Moessner, Y.-M. Lu, O. Erten Phys. Rev. Research 5, L022062 (2023).
(5) A. Vijayvargia, U. Seifert, O. Erten Phys. Rev. B 109, 024439 (2024).

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Workshop / Seminar Wed, 27 Mar 2024 12:24:41 -0400 2024-04-11T16:00:00-04:00 2024-04-11T17:00:00-04:00 West Hall Interdisciplinary QC/CM Seminars Workshop / Seminar West Hall
Interdisciplinary QC-CM Seminar (April 18, 2024 4:00pm) https://events.umich.edu/event/120741 120741-21845201@events.umich.edu Event Begins: Thursday, April 18, 2024 4:00pm
Location: West Hall
Organized By: Interdisciplinary QC/CM Seminars

TBA

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Workshop / Seminar Tue, 26 Mar 2024 06:27:59 -0400 2024-04-18T16:00:00-04:00 2024-04-18T17:00:00-04:00 West Hall Interdisciplinary QC/CM Seminars Workshop / Seminar West Hall