Room-temperature Pauli spin blockade and current rectification in 15-13-15 armchair graphene nanoribbon heterostructures

In this study, we investigate the electronic structures of 13-11-13 and 15-13-15 armchair graphene nanoribbon (AGNR) superlattices (SLs) using a tight-binding model. We demonstrate that the conduction and valence subbands of 15-13-15 AGNR SLs can be accurately described by the Su-Schrieffer-Heeger model, with topologically protected interface states emerging at the junctions between 15-AGNR and 13-AGNR segments. These interface states enable the formation of quantum dot arrays with energy levels well separated from bulk states, making them promising candidates for high-temperature solid-state quantum processors. For 15-13-15 AGNRH segments, we observe both localized zigzag edge states and topologically protected interface states under longitudinal electric fields, with the latter providing efficient tunneling channels in contrast to the less conductive edge states. We further explore nonlinear charge transport through these interface states under Pauli spin blockade, showing that tunneling current spectra reveal charge stability diagrams and Coulomb blockade oscillations, consistent with experimental findings in other serial double quantum dot systems. Additionally, we examine the impact of orbital offsets on tunneling current rectification and demonstrate that significant current rectification is achieved over a wide temperature range when level broadening is optimized. These results highlight the potential of 15-13-15 AGNRHs for robust spin-current conversion and applications in quantum devices, offering advantages over other proposed structures due to precise tunability of key parameters via bottom-up synthesis techniques and the ease of two-gate electrode integration.