PHYSICS DISSERTATION DEFENSE: Jesse C. Hoke

Ph.D. Candidate:  Jesse C. Hoke

Research Advisor:  Benjamin E. Feldman

Date: April 03, 2024

Time: 3:00 PM - 5:00 PM PST

Location: Y2E2 Room 299

Zoom Link:  https://stanford.zoom.us/j/2350230821

Zoom Password: email nickswan [at] stanford.edu (nickswan[at]stanford[dot]edu) for password.

 Title: Exploring the Magic of Twisted Trilayer Graphene

Abstract: The twist angle between adjacent van der Waals layers is a powerful tuning knob to engineer electronic band structure and induce strong electron-electron interactions. Incorporating three van der Waals layers with two independent twist angles enables additional tunability. In this talk I will discuss three recent experiments on different twisted trilayer graphene (TTG) heterostructures. The first is on transport measurements of a twist-decoupled magic angle twisted bilayer graphene (MATBG) and monolayer graphene (MLG) device, which realizes independently tunable flat and dispersive bands. By studying the backscattering between counter-propagating edge states in a magnetic field, we can deduce the relative spin polarization of their edge modes. To better understand how correlated states depend on the twist angle between layers, I will present local measurements of a TTG device with a scanning single electron transistor (SET) as a function of spatial position. This allows us to systematically map out its electronic structure and topology as a function of the twist angle. Lastly, I will present some of our most recent work imaging helical trilayer graphene (HTG) at the supermoire scale and reveal that it locally relaxes into large domains of a single-moire periodicity separated by conductive domain walls. Each of these examples highlight the strong tunability and variety of different electronic phases that can be realized by tuning two independent twist angles in moire heterostructures.