Quantum transport and frustrated magnetism in strained graphene with Christophe De Beule

Lattice deformations in graphene couple to the low-energy Dirac electrons as effective scalar and gauge fields. In this talk, I will discuss how strain-induced pseudogauge fields can be leveraged to design straintronics devices for studying quantum interference and strongly-correlated electronic phases.

First, I will introduce pseudogauge fields in graphene, and discuss the role of acoustic and optical deformations [1]. I will then present a theory for a simple straintronics device that consists of graphene suspended between two misaligned gate electrodes, resulting in a pseudogauge barrier from localized uniaxial strain. This device hosts gate-tunable conductance resonances, a 1D channel of valley chiral or counterpropagating modes that provides a simple platform for Luttinger liquid physics, and sublattice-resolved Friedel oscillations. Finally, I will show that our theory explains a recent experiment in terms of a hybrid pseudogauge and electrostatic interferometer [2].

In the second part, I will show how topological flatbands can be engineered in bilayer graphene with periodic strain by depositing it on a patterned hBN substrate [3]. I will share experimental results that show evidence of frustrated magnetism in this system, discuss the microscopic origin of the local spins, and show that classical Monte Carlo spin-ice simulations can explain the observed hysteresis in terms of emergent magnetic charges.

[1] Elastic Screening of Pseudogauge Fields in Graphene, C. De Beule, R. Smeyers, W. N. Luna, E. J. Mele, and L. Covaci, Phys. Rev. Lett. 134, 046404 (2025).
[2] Gate-Tunable Resonances and 1D Channel in a Graphene Nanoslide, C. De Beule, M.-H. Liu, B. Partoens, and L. Covaci, arXiv:2512.22982 (2025).
[3] Frustrated Magnetism in Strain-Patterned Graphene Superlattices, Y.-C. Hsieh, W.-H. Kao, C. De Beule, et al. Under review in Nature (2025).

This lecture was made possible by the William C. Ferguson Fund.