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SUMMARY:3D quantum Hall effects in Dirac loops - Prof. Bruno Uchoa\, The U
 niversity of Oklahoma
DTSTART:20190124T141500Z
DTEND:20190124T151500Z
UID:TALK116959@talks.cam.ac.uk
CONTACT:Katarzyna Macieszczak
DESCRIPTION:Nodal line semimetals describe a class of 3D systems where the
  low energy bands have Dirac quasiparticles along a closed line in momentu
 m space (Dirac loop) rather than a discrete set of Dirac points [1]. Away 
 from half filling\, the Fermi surface is a toroid. In the presence of spin
  orbit coupling effects\, this system can behave as a strong topological i
 nsulator\, with topologically protected surface states.  In spite of being
  three dimensional\, this system has Landau level quantization at finite f
 ield for certain field geometries. One conceptually interesting family of 
 lattice models that describes this physics is the family of the hyperhoney
 comb lattices\, which form  3D structures of crossed 1D chains where all s
 ites have the same planar trigonal connectivity of graphene. \nIn this tal
 k\, I will show that Coulomb interactions could drive the system to show a
 n anomalous quantum Hall effect (AQHE) [2]\, with current loops that produ
 ce zero net flux in the 3D unit cell. I will show that in the AQH state\, 
 because of lack of inversion symmetry\, the Haldane mass has nodes along t
 he nodal line\, giving rise to pairs of Weyl points connected by Fermi arc
 s. I will discuss the anomalous Hall conductivity of this system and the c
 onnections with strain field deformations encoded in the elastic Hall visc
 osity [3].\n\n[1] K. Mullen\, B. Uchoa\, D. Glatzhofer\, Phys. Rev. Lett. 
 115\, 026403 (2015).\n\n[2] S. W. Kim\, K. Seo\,  B. Uchoa\, Phys. Rev. B 
 97\, 201101 (R) (2018).\n\n[3] S. W. Kim\, B. Uchoa\, arXiv:1901.00574 (20
 19). 
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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