Interplay of filling fraction and coherence in symmetry broken graphene p-n junction

Abstract

Graphene p–n junction (PNJ) with co-propagating spin-valley polarized quantum Hall (QH) edges is a promising platform for studying electron interferometry. Though several conductance measurements have been attempted for such PNJs, the edge dynamics of the spin-valley symmetry broken edge states remain unexplored. In this work, we present the measurements of conductance together with shot noise, an ideal tool to unravel the dynamics, at low temperature, in a dual graphite gated hexagonal boron nitride encapsulated high mobility graphene device. The conductance data show that the symmetry broken QH edges at the PNJ follow spin selective equilibration. The shot noise results as a function of both p and n side filling factors reveal the unique dependence of the scattering mechanism. Remarkably, the scattering is found to be fully tunable from incoherent to coherent regime with the increasing number of QH edges at the PNJ, shedding crucial insights of edge dynamics.