Magnetic field anisotropies in charge transport in graphene strain superlattices

Strain superlattices in graphene have been predicted to lead to novel quantum phenomena such as generation of pseudomagnetic fields, valley Hall currents and topological edge states. Previous [1,2] transport measurements on a strain superlattice (SL) of graphene, created by stacking it on silica nanosphere (NS) self-assemblies, revealed strain-tunable dips in two-probe conductance resulting from SL miniband effects and an average pseudo-magnetic field of ~4T. We now report multiterminal transport measurements in these graphene-NS systems. We observe a magnetic field anisotropy in both longitudinal and Hall resistances, and non-local signals, which may be a result of an edge current flowing through the device. This might indicate an underlying symmetry breaking and lifting of the valley degeneracy in these systems.

This research was primarily supported by the NSF through the University of Illinois at Urbana-Champaign Materials Research Science and Engineering Center under the grants DMR-1720633 and DMR-2309037.

[1] Y. Zhang et al, npj 2D Materials and Applications 2, 31 (2018)

[2] Y. Zhang et al., App. Phys. Lett. 115, 143508 (2019)