Substantially enhanced robustness of quantum Hall effect in graphene on LaAlO3/SrTiO3 heterostructure

Hybrid structures comprised of monolayer graphene and LaAlO₃/SrTiO₃ heterostructure are fabricated. By exploiting LaAlO₃ as a natural dielectric layer, an ultra-large capacitance of up to 1.59 μF cm^-2 is obtained, enabling significantly reduced operating gate voltage for this graphene-based field-effect device. Furthermore, well-defined quantum Hall effects (QHEs) are realized at relatively modest conditions, e.g. at 1.5 K/1.5 T, and 150 K/7 T. The substantially enhanced robustness of QHE is attributed to the suppression of multiple scattering processes in graphene with the help of LaAlO₃/SrTiO₃. These results make graphene on LaAlO₃/SrTiO₃ a viable choice for developing quantum metrology of resistance.