QUANTUM MATERIALS AND DEVICES SEMINARS: "Carbon with a twist: electrons and phonons in moiré graphene bilayers"
DIPC Seminars
- Speaker
-
Hector Ochoa, Columbia University, USA
- When
-
2021/09/15
17:00 - Place
- Online Seminar, Donostia International Physics Center
- Add to calendar
- iCal
Sliding and twisting the layers of Van der Waals materials give rise to
superstructures with new physics, such as the plethora of strongly correlated
phenomena (superconductivity included) observed in twisted bilayer graphene.
In this talk, I will review our current understanding of how electrons behave
in moiré patterns, and how disorder and phonons may affect this behavior. I
will argue that the long-wavelength dynamics of these generically
incommensurate structures are dominated by new collective modes: phasons [1].
These modes correspond to coherent superpositions of optical phonons
describing the sliding motion of stacking domain walls separating regions of
partial interlayer commensuration. I will discuss various physical
consequences of this observation, including the widespread presence of
structural disorder in the form of strain accumulated between the layers [2].
At neutrality, these tensions favor orbital magnetic order with charged vortex
excitations [3], which may explain some of the disparities observed in
transport measurements in different devices.
[1] H. Ochoa, Phys. Rev. B 100, 155426 (2019).
[2] H. Ochoa and R. M. Fernandes, arXiv:2108.10342.
[3] H. Ochoa, Phys. Rev. B 102, 201107 (2020).
Host: Miguel A. Cazalilla
REGISTRATION REQUIRED
https://dipc-org.zoom.us/meeting/register/tZAqceGqrzMqE9fPWdhzaKxoIscCspVlFJ4Y