Cornell University

This is a past event. Its details are archived for historical purposes.

The contact information may no longer be valid.

Please visit our current events listings to look for similar events by title, location, or venue.

Quantum Theory Seminar - Hart Goldman (University of Chicago)

Friday, March 29, 2024 at 3:30pm to 4:30pm

Clark Hall 701, Clark Hall, 701

Title: Composite fermions and the fractional quantum anomalous Hall effect

Abstract:

Recent experiments have revealed evidence for fractional quantum anomalous Hall (FQAH) states at zero magnetic field in a growing number of moiré materials. In this talk, I will present a unified theoretical framework for understanding the emergence of FQAH phases in terms of composite fermions, which in the past have played a crucial organizing role in the  phenomenology of 2d electron gases at high magnetic fields. A central prediction of this framework is a non-Fermi liquid metal of composite fermions at even-denominator fillings, which is the parent of the observed FQAH states. To this end, I will present exact diagonalization evidence for such anomalous composite Fermi liquid (ACFL) states at zero magnetic field in twisted MoTe2 bilayers, at fillings n = 1/2 and n = 3/4, and I will argue that these ACFLs play a central role in the FQAH phase diagram. I will also develop a long wavelength theory for ACFL phases, which offers concrete experimental predictions that I will discuss in relation to current measurements. For example, upon doping the composite Fermi sea, one obtains a Jain sequence of FQAH states consistent with those observed experimentally, as well as a new type of commensurability oscillations originating from the superlattice potential intrinsic to the system. Finally, I will discuss how these ideas can launch us into addressing the exciting new questions and research directions in this emerging field. 

Faculty Hosts: Eun-Ah KimChao-Ming Jian, and Debanjan Chowdhury

Streaming site:

https://www.youtube.com/@quantumtheoryseminar6651/streams

Subscribe
Google Calendar iCal Outlook
Event Type

Seminar

Departments

LASSP

University Themes

Research

Tags

quantum_site, lassp, quantum_lassp

Cost

Free

Contact E-Mail

lassp-seminars@cornell.edu

Contact Name

Meredith Collins

Speaker

Yasaman Bahri

Speaker Affiliation

Google DeepMind

Dept. Web Site

https://www.lassp.cornell.edu/

Disability Access Information

If you need accommodations to participate in this event, please contact us as soon as possible.

Open To

Open to the Public

Recent Activity