About the Project
To deliver on the promises of nanoscale quantum materials, we must understand the strong interdependence between their mechanics and electronics. Atomically-thin 2D materials have shown recently that controlling their mechanical configuration (via heterostructures) makes a dramatic different in their electronic behavior. We have a unique experimental capability to study suspended 2D crystals, where we apply tunable and smooth mechanical strain, to control their quantum transport. In the honeycomb carbon lattices, mechanical strains create both scalar and pseudomagnetic potentials acting on the pseudospin of Dirac electrons, and offer the possibility to create quantum straintronics devices.
In bilayer graphene, each K valley has four Dirac cones at low energy. Uniaxial strain is expected to modify this topology are reduce the degeneracy to two (Liftshitz transition). This transition should have signatures in ballistic conductivity, and magnetotransport. Magic angle bilayer graphene is made of two monolayers stamped onto one another with a 𝜃 ≈1.05 degree rotation (the superlattice leads to flat electronic bands). It displays unconventional superconductivity, and offers unique opportunities to engineer and explore the superconducting phase diagram. Uniaxial straining is expected to accurately tune 𝜃 in-situ and control the phase transitions.
Making modifications to our instrumentation, to clamp the samples along three sides, we will generate tri-axial strain fields. We aim to make the first demonstration of large and tunable pseudomagnetic fields (10s of Tesla) in graphene. The combination of pseudomagnetic fields (opposite in K and K’) and real magnetic field (same in K and K’), will make it possible to create a zero total field in one of the two valleys, and generate valley-polarized currents. These charge neutral valley currents are measurable, and would find applications in quantum electronics.
This PhD project is be part of the “QSciTech: Bridging the Gap between Quantum Science and Quantum Technologies” (NSERC-CREATE training program). This program includes a network of 11 research teams in quantum science and technology across Canada, offers transdisciplinary courses, and will offer you a one-semester-long paid industrial internship as part of your PhD.
For information about this specific position, please contact Prof. Alex Champagne ([Email Address Removed]). For information about our graduate programs in general, please contact Prof. Valter Zazuvobits ([Email Address Removed]).
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