Cornell University

During the spring semester, in-person concerts, events and lectures that involve outside guests will not be held, per the university’s COVID-19 travel and visitor policy.

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.

LASSP & AEP Seminar - Stevan Nadj-Perge - California Institute of Technology

Tuesday, May 18, 2021 at 12:20pm

Virtual Event

Host: Katja Nowack

Title: Superconductivity, Topology and Correlated Insulators in Magic-Angle Twisted Bilayer Graphene–How Much Magic is Needed?


Twisted bilayer graphene (TBG) with a rotational misalignment angle close to the magic angle of 1.1 degrees features isolated flat electronic bands that host various correlated insulating, superconducting, ferromagnetic, and topological phases. However, the origin of these phases and the relation between them remain elusive because of their sensitivity to microscopic details in TBG, such as strain, twist angle disorder, and dielectric environment.

In this talk, I will discuss our transport and scanning tunneling microscopy (STM) experiments that explore the stability of various correlated phases with respect to twist angle and its deviation from the magic-angle value. First, I will present our transport data showing that, by placing TBG on a tungsten diselenide (WSe2) monolayer, the superconductivity can be stabilized down to twist angles as small as 0.79 degrees. Importantly, for angles in this range, both the correlated insulating states and the band gaps between flat and dispersive bands disappear, leading to metallic behavior across the accessible range of electron density. These findings significantly constrain the theoretical explanations for the emergence of superconductivity in TBG and its relation to other correlated phases. In the second part of the talk, we will discuss STM measurements that reveal how the interplay between strong interactions and non-uniform charge distribution in TBG leads to the flattening of the TBG bands. Close to the magic angle, this interaction-driven band flattening gives rise to robust correlated insulating and topological Chern phases that emerge in zero and finite magnetic fields. Our results highlight the role of band structure renormalization, alongside spontaneous symmetry breaking, in the formation of strongly correlated and topological TBG phases.

Dial-In Information

Topic: LASSP & AEP Seminar - Stevan Nadj - Perge -California Institute of Technology
Time: May 18, 2021 12:20 PM Eastern Time (US and Canada)

Join Zoom Meeting

Meeting ID: 951 9032 6192
Passcode: 677690
One tap mobile
+16465189805,,95190326192# US (New York)
+16468769923,,95190326192# US (New York)

Dial by your location
        +1 646 518 9805 US (New York)
        +1 646 876 9923 US (New York)
        +1 651 372 8299 US (Minnesota)
        +1 786 635 1003 US (Miami)
        +1 301 715 8592 US (Washington DC)
        +1 312 626 6799 US (Chicago)
        +1 470 250 9358 US (Atlanta)
        +1 470 381 2552 US (Atlanta)
        +1 669 900 6833 US (San Jose)
        +1 720 928 9299 US (Denver)
        +1 971 247 1195 US (Portland)
        +1 253 215 8782 US (Tacoma)
        +1 346 248 7799 US (Houston)
        +1 602 753 0140 US (Phoenix)
        +1 669 219 2599 US (San Jose)
Meeting ID: 951 9032 6192
Find your local number:

Join by SIP

Join by H.323 (US West) (US East) (India Mumbai) (India Hyderabad) (Amsterdam Netherlands) (Germany) (Australia Sydney) (Australia Melbourne) (Singapore) (Brazil) (Canada Toronto) (Canada Vancouver) (Japan Tokyo) (Japan Osaka)
Meeting ID: 951 9032 6192
Passcode: 677690

Join by Skype for Business

Google Calendar iCal Outlook
Event Type



LASSP, Applied and Engineering Physics


lassp_and_aep_seminar, lassp

Contact E-Mail

Contact Name

Lea Reagan

Contact Phone



Stevan Nadj-Perge Assistant Professor of Applied Physics and Materials Science

Speaker Affiliation

California Institute of Technology

Dept. Web Site

Open To


Recent Activity