Charge, spin and valley Hall effects in disordered graphene reviewed

December 23, 2016 - In the recent review article, Prof. Nikolic and collaborators from Grenoble and Barcelona provide comprehensive coverage of different types of Hall effects, both in their classical and quantized versions, observed in graphene where electrons can scatter elastically from adatoms, vacancies and impurities or inelastically from lattice vibrations. 

The discovery of the integer quantum Hall effect in the early eighties of the last century, with highly precise quantization values for the Hall conductance in multiples of e2/h, has been the first fascinating manifestation of the topological state of matter driven by magnetic field and disorder, and related to the formation of non-dissipative current flow. Throughout the 2000’s, several new phenomena such as the spin Hall effect and the quantum spin Hall effect were confirmed experimentally for systems with strong spin-orbit coupling effects and in the absence of external magnetic field. More recently, the Zeeman spin Hall effect and the formation of valley Hall topological currents have been introduced for graphene-based systems, under time-reversal or inversion symmetry-breaking conditions, respectively. The published review article covers of all these Hall effects in disordered graphene from the perspective of numerical simulations of quantum transport in two-dimensional bulk systems (by means of the Kubo formalism) and multiterminal nanostructures (by means of the Landauer-B¨uttiker scattering and non-equilibrium Green’s function approaches). In contrast to usual two-dimensional electron gases in semiconductor heterostructures, the presence of defects in graphene generates more complex electronic features such as electron-hole asymmetry, defect-induced resonances in the electron density of states or percolation effect between localized impurity states, which, together with extra degrees of freedom (sublattice pseudospin and valley isospin), bring a higher degree of complexity and enlarge the transport phase diagram.

ABOUT NIKOLIC GROUP

Several Chapters in this review article are based on the work of graduate students at the University of Delaware: P.-H. Chang, C.-L. Chen and J. M. Marmolejo-Tejada. For more informatrion about theoretical and computational condensed matter and nanophysics reseach conducted by Nikolic group visit their Website.

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La Rivista del Nuovo Cimento is an international peer-reviewed journal. It publishes monographs in all fields of physics. These monographies aim at presenting the state of the art of topical subjects of relevant interest for the community. Usually, authors are invited and topics suggested by the Deputy Editors-in-Chief, but also spontaneous submissions are examined. La Rivista del Nuovo Cimento is associated to The European Physical Journal. Articles in La Rivista del Nuovo Cimento are abstracted in ISI Thomson Science Citation Index, INSPEC, INSPIRE, Chemical Abstracts, Scopus.