Weyl semimetal in a topological insulator multilayer.

We propose a simple realization of the three-dimensional (3D) Weyl semimetal phase, utilizing a multilayer structure, composed of identical thin films of a magnetically doped 3D topological insulator, separated by ordinary-insulator spacer layers. We show that the phase diagram of this system contains a Weyl semimetal phase of the simplest possible kind, with only two Dirac nodes of opposite chirality, separated in momentum space, in its band structure. This Weyl semimetal has a finite anomalous Hall conductivity and chiral edge states and occurs as an intermediate phase between an ordinary insulator and a 3D quantum anomalous Hall insulator. We find that the Weyl semimetal has a nonzero dc conductivity at zero temperature, but Drude weight vanishing as T(2), and is thus an unusual metallic phase, characterized by a finite anomalous Hall conductivity and topologically protected edge states.

[1]  Fisher,et al.  Integer quantum Hall transition: An alternative approach and exact results. , 1994, Physical review. B, Condensed matter.

[2]  Ashvin Vishwanath,et al.  Subject Areas : Strongly Correlated Materials A Viewpoint on : Topological semimetal and Fermi-arc surface states in the electronic structure of pyrochlore iridates , 2011 .

[3]  S. Murakami.  Phase transition between the quantum spin Hall and insulator phases in 3D: emergence of a topological gapless phase , 2007, 0710.0930.

[4]  C. Kane,et al.  Topological Insulators , 2019, Electromagnetic Anisotropy and Bianisotropy.

[5]  R. Cava,et al.  Observation of a large-gap topological-insulator class with a single Dirac cone on the surface , 2009 .

[6]  H. Nielsen,et al.  Absence of neutrinos on a lattice: (I). Proof by homotopy theory , 1981 .

[7]  H. Nielsen,et al.  Absence of neutrinos on a lattice: (II). Intuitive topological proof , 1981 .

[8]  Z. K. Liu,et al.  Massive Dirac Fermion on the Surface of a Magnetically Doped Topological Insulator , 2010, Science.

[9]  E. J. Mele,et al.  Z2 topological order and the quantum spin Hall effect. , 2005, Physical review letters.

[10]  Xi Dai,et al.  Crossover of the three-dimensional topological insulator Bi 2 Se 3 to the two-dimensional limit , 2010 .

[11]  Xiao-Liang Qi,et al.  Aharonov-Bohm interference in topological insulator nanoribbons. , 2009, Nature materials.

[12]  Shou-Cheng Zhang,et al.  Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells , 2006, Science.

[13]  L. Balents,et al.  Topological invariants of time-reversal-invariant band structures , 2007 .

[14]  Liang Fu,et al.  Topological insulators in three dimensions. , 2006, Physical review letters.

[15]  Wei Zhang,et al.  Quantized Anomalous Hall Effect in Magnetic Topological Insulators , 2010, Science.

[16]  Quantum Phase Transitions from Topology in Momentum Space , 2006, cond-mat/0601372.

[17]  Leon Balents,et al.  Mott physics and band topology in materials with strong spin-orbit interaction , 2009, 0907.2962.

[18]  EMERGENT CPT VIOLATION FROM THE SPLITTING OF FERMI POINTS , 2004, hep-th/0403037.

[19]  X. Dai,et al.  Quintuple-layer epitaxy of thin films of topological insulator Bi2Se3 , 2009 .

[20]  Kai-Yu Yang,et al.  Quantum Hall effects in a Weyl semimetal: Possible application in pyrochlore iridates , 2011, 1105.2353.

[21]  Conyers Herring,et al.  Accidental Degeneracy in the Energy Bands of Crystals , 1937 .

[22]  G. Volovik,et al.  The Universe in a Helium Droplet , 2003 .