Emergent Thermal Strain-Induced Pseudomagnetic Fields and Shubnikov–de Haas Beating Patterns in Encapsulated Graphene in Extraordinary Magnetoresistance Geometry

Strain has been theoretically predicted and experimentally demonstrated as a tool for modifying the properties of graphene and two-dimensional (2D) materials through the creation of a pseudomagnetic field (PMF). The practical introduction of a controllable PMF has so far presented a significant challenge. In this study, we present evidence for the presence of PMF induced by thermal strain in extraordinary magnetoresistance (EMR) devices based on monolayer graphene encapsulated in hexagonal boron nitride. Signal processing methods permit the differentiation of weak effects obscured within the signals. Investigations of the beating patterns in the Shubnikov-de Haas oscillations observed in electrical transport measurements complemented by finite element simulations and quantum transport calculations indicate the existence of a PMF of 0.1-0.2 T. The magnitude and pattern of strain and PMF in such geometry are flexible to control compared to other methods. The devices under investigation also exhibit an enhanced EMR effect, commensurability magnetoresistance effect, and weak localization and antilocalization due to spatial variation of strain in the device. The EMR geometry represents an intriguing and promising avenue for both fundamental physics research and applications including magnetic field sensors, straintronics and valleytronics, and 2D material and thin-film semiconductor industries.