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BEGIN:VEVENT
UID:1-561@lptms.universite-paris-saclay.fr
DTSTART:20171115T140000Z
DTEND:20171115T151500Z
DTSTAMP:20171113T120758Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-excepti
 onnel-du-lptms-natalia-menezes-silva-da-costa/
SUMMARY:Séminaire exceptionnel du LPTMS: Natalia Menezes Silva Da Costa - 
 LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay - 15 Nov 17 1
 4:00
DESCRIPTION:Quantum field theory in low-dimensional condensed-matter system
 s\nNatália Menezes Silva Da Costa (Utrecht University)\nIn this talk I wi
 ll present two examples of how quantum field theories may be applied to de
 scribe the long wavelength regime of condensed-matter systems.\n\nThe firs
 t example [1] concerns the study of electronic interactions on the boundar
 y of a two-dimensional time-reversal-invariant topological insulator. Whil
 e the bulk of this two-dimensional material is insulating\, the boundary e
 xhibits propagating modes that may be described in terms of a one-dimensio
 nal Dirac theory.  By assuming that there is an underlying electromagneti
 c theory mediating the e-e interaction on the edges\, and by employing a d
 imensional reduction procedure\, I will show that the effective one-dimens
 ional theory is a non-Fermi liquid\, known as the helical Luttinger liquid
  (HLL).  This HLL resembles a theory of free bosons\, however\, with a pa
 rameter in its kinematics that indicates the strength of the e-e interacti
 ons. Within the quantum-field theoretical formalism\, I will show that suc
 h parameter can be written in terms of the fine structure constant\, which
  allows one not only to predict its value but also to manipulate the natur
 e attractive/repulsive of the interaction.\n\nThe second example [2] conce
 rns the topological response of a fermionic model defined on the Lieb latt
 ice in presence of an electromagnetic field. The tight-binding model is bu
 ilt in terms of three species of spinless fermions and supports a topologi
 cal Varma phase due to the spontaneous breaking of time-reversal symmetry.
  In the low-energy regime\, the emergent effective Hamiltonian coincides w
 ith the so-called Duffin-Kemmer-Petiau (DKP) Hamiltonian\, which describes
  relativistic pseudospin-0 quasiparticles and goes beyond the commonly stu
 died spin-1/2 Dirac/Weyl paradigm. By considering a minimal coupling betwe
 en the DKP quasiparticles and an external Abelian gauge field\, I will pre
 sent both the Landau-level spectrum and the emergent Chern-Simons theory. 
 The corresponding Hall conductivity reveals an atypical quantum Hall effec
 t\, which can be simulated in an artificial Lieb lattice.\n\n[1] N. Meneze
 s\, G. Palumbo and C. Morais Smith\, Sci. Rep. 7\, 14175 (2017).\n\n[2] N.
  Menezes\, C. Morais Smith and G. Palumbo\, arXiv:1710.07916 (2017).
CATEGORIES:seminars
LOCATION:LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay\, 15 
 Rue Georges Clemenceau\, Orsay\, 91405\, France
GEO:48.698185;2.181768
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  Orsay\, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=LPTMS\, salle 201\, 2è
 me étage\, Bât 100\, Campus d'Orsay:geo:48.698185,2.181768
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