The emergence of multiple Dirac cones in hexagonal boron nitride (hBN)−graphene heterostructures is particularly attractive because it offers potentially better landscape for higher and versatile transport properties than the primary Dirac cone. However, the transport coefficients of the cloned Dirac cones are yet not fully characterized and many open questions, including the evolution of charge dynamics and impurity scattering responsible for them, have remained unexplored. We study these properties using conductance, 1/f noise and quantum transport like localization physics to explore the Berry phase etc. Very recently the field got boost after the discovery of superconductivity in magic-angle (1.1o) twisted bilayer graphene (MATBG), twistronics has become one of the towering research interests in the field of mesoscopic physics. In addition to superconductivity, MATBG exhibits a plethora of exotic phases including correlated insulators, topological phases, Chern insulators, cascaded electronic transition etc. These novel phases result from the interplay between strong electron-electron interactions and band topology. When two monolayer graphenes are stacked together with a relative twist angle, a Moiré lattice forms, giving rise to a vast renormalization of the band structure compared to the traditional AB-stacked bilayer graphene. When this twist angle is close to theoretically predicted magic angle, two nearly flat lower energy bands are formed, resulting in a density of states thousand times higher than that of bilayer graphene. The flattening of bands minimizes the kinetic energy providing a vast breeding ground for exotic physics. The field of twistronics progressively found its way to other layered 2D materials like MoS2, WSe2 etc. To study the angle tunable electrical and thermal transport in TBG and TDBLG is our primary interest.
References:
Physical Review B 98 (15), 155408
(Top-left): Moir superlattice of graphene on hBN. Schematic of the measurement setup with top gated device. (Top right): Moire band structure from tight binding calculation. (Middle-left): power spectral density of 1/f noise. (Middle-right): Resistance and normalized noise around primary Dirac and secondary Dirac point. (Bottom): Correspondence between resistance and 1/f noise as a function of bottom and top gate.
(Top): Moire superlattice structure of graphene on hBN. Gate response of the device with primary and cloned Dirac cones. (Bottom); Schematic of localization physics with time reversal paths. Magnetoresistance around cloned and primary Dirac with contrasting results.
