Spin-orbit coupling, edge states and quantum spin Hall criticality due to Dirac fermion confinement: The case study of graphene - Condensed Matter > Mesoscale and Nanoscale PhysicsReport as inadecuate




Spin-orbit coupling, edge states and quantum spin Hall criticality due to Dirac fermion confinement: The case study of graphene - Condensed Matter > Mesoscale and Nanoscale Physics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We propose a generalized Dirac fermion description for the electronic stateof graphene terminated by a zigzag edge. This description admits a spin-orbitcoupling needed to preserve time-reversal invariance of the zigzag confinement,otherwise, for spinless particles, showing the parity anomaly typical ofquantum electrodynamics in 2+1 dimensions. At a certain critical strength thespin-orbit coupling induces a phase transition of the quantum-spin-Hall type.It is manifested by a novel type of the edge states consisting of a Kramers-pair of counter-propagating modes with opposite spin orientations. Such edgestates are capable of accumulating an integer spin in response to a transverseelectric field in the absence of a magnetic one. They exist without anyexcitation gap in the bulk, due to which our system stands out among otherquantum spin Hall systems studied earlier. We show that at the transition thelocal density of states is discontinuous and its energy dependence reflects thephase diagram of the system.



Author: Grigory Tkachov, Martina Hentschel

Source: https://arxiv.org/







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