APS March Meeting 2016
Volume 61, Number 2
Monday–Friday, March 14–18, 2016;
Baltimore, Maryland
Session K3: Weyl Topological Semimetals: Theory and Experiment
8:00 AM–11:00 AM,
Wednesday, March 16, 2016
Room: Ballroom III
Sponsoring
Units:
DCMP DMP
Chair: Arun Bansil, Northeastern University
Abstract ID: BAPS.2016.MAR.K3.3
Abstract: K3.00003 : Discovery of Weyl fermion semimetal and topological Fermi arc quasiparticles in TaAs, NbAs, NbP, TaP and related materials
9:12 AM–9:48 AM
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Abstract
Author:
M. Zahid Hasan
(Princeton Univ)
Topological matter can host Dirac, Majorana and Weyl fermions as
quasiparticle modes on their boundaries. First, I briefly mention the basic
theoretical concepts defining insulators and superconductors where
topological surface state modes are robust only in the presence of a gap
(Hasan {\&} Kane; Rev. of Mod. Phys. 82, 3045 (2010)). In these systems
topological protection is lost once the gap is closed turning the system
into a trivial metal. A Weyl semimetal is the rare exception in this scheme
which is a topologically robust metal (semimetal) whose low energy emergent
excitations are Weyl fermions. In a Weyl fermion semimetal, the chiralities
associated with the Weyl nodes can be understood as topological charges,
leading to split monopoles and anti-monopoles of Berry curvature in momentum
space. This gives a measure of the topological strength of the system. Due
to this topology a Weyl semimetal is expected to exhibit 2D Fermi arc
quasiparticles on its surface (Wan et.al., 2011). These arcs (``fractional''
Fermi surfaces) are discontinuous or disjoint segments of a two dimensional
Fermi contour, which are terminated onto the projections of the Weyl fermion
nodes on the surface we have observed experimentally in TaAs, NbAs, NbP
class of materials (Xu, Belopolski et.al., Science 349, 613 (2015); Xu,
Alidoust et.al., Nature Phys. (2015); Xu, Belopolski et.al., Science Adv.
(2015), Belopolski, Xu et.al., arXiv (2015)) following our theoretical
predictions (Huang, Xu, Belopolski et.al., Nature Commun. 6:7373 (2015),
submitted in November 2014). Our theoretical predictions (Nature Commun.
2015) and experimental demonstrations (Science 2015, Nature Physics 2015,
Science Advances 2015) reveal that these Fermi arc quasiparticles can only
live on the boundary of a 3D crystal which collectively represents the
realization of a new state of quantum matter beyond our earlier work on
Fermi arcs in topological materials (Xu, Liu, Kushwaha et.al., Science 347,
294 (2015), adv.online (2014)). This work is in collaboration with Su-Yang
Xu, Ilya Belopolski, Nasser Alidoust, Madhab Neupane, Chenglong Zhang, Raman
Sankar, Shin-Ming Huang, Chi-Cheng Lee, Guoqing Chang, BaoKai Wang, Guang
Bian, Hao Zheng, Daniel S. Sanchez, Fangcheng Chou, Hsin Lin, Shuang Jia,
Titus Neupert. This work is supported by GBMF and U.S. DOE.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2016.MAR.K3.3