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Diffusion of Dirac fermions across a topological merging transition in two dimensions

Abstract : A continuous deformation of a Hamiltonian possessing at low energy two Dirac points of opposite chiralities can lead to a gap opening by merging the two Dirac points. In two dimensions, the critical Hamiltonian possesses a semi-Dirac spectrum: linear in one direction but quadratic in the other. We study the transport properties across such a transition, from a Dirac semimetal through a semi-Dirac phase toward a gapped phase. Using both a Boltzmann approach and a diagrammatic Kubo approach, we describe the conductivity tensor within the diffusive regime. In particular, we show that both the anisotropy of the Fermi surface and the Dirac nature of the eigenstates combine to give rise to anisotropic transport times, manifesting themselves through an unusual matrix self-energy.
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Contributor : Edmond Orignac Connect in order to contact the contributor
Submitted on : Tuesday, April 5, 2016 - 5:38:07 PM
Last modification on : Monday, September 13, 2021 - 4:49:20 PM

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Pierre Adroguer, David Carpentier, Gilles Montambaux, Edmond Orignac. Diffusion of Dirac fermions across a topological merging transition in two dimensions. Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2016, 93 (12), pp.125113. ⟨10.1103/PhysRevB.93.125113⟩. ⟨ensl-01298346⟩



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