Weyl semimetal phase in the non-centrosymmetric compound TaAs

Abstract

. This discovery not only confirms TaAs as a 3D TWS, but also provides an ideal platform for realizing exotic physical phenomena (for example, negative magnetoresistance, chiral magnetic e ects and the quantum anomalous Hall e ect) which may also lead to novel future applications.

Topological semimetals with helicoid surface states

“…On the surface of a Weyl semimetal, the Fermi surface consists of open arcs connecting the projection of bulk Weyl points onto the surface Brillouin zone [2], instead of closed loops. The presence of Fermi arcs on the surface is a remarkable property that directly reflects the nontrivial topology of the bulk, and plays a key role in the experimental identification of Weyl semimetals [32,33,36]. In contrast, as shown by recent theoretical works [18,21,23,24,28,48,49], existing Dirac and nodal line semimetals do not have robust Fermi arcs that are stable against symmetry-allowed perturbations.…”

“…The nontrivial topology gives rise to anomalous bulk properties of topological semimetals such as the chiral anomaly [3][4][5]. Several classes of topological semimetals have been theoretically proposed so far, including Weyl, [2,[6][7][8][9][10][11][12][13], Dirac [14][15][16][17] and nodal line semimetals [7,[17][18][19][20][21][22][23][24][25][26][27][28][29][30], some among which have been experimentally observed [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47].Surface states of topological semimetals have attracted much attention. On the surface of a Weyl semimetal, the Fermi surface consists of open ar...…”

Evolution of the topologically protected surface states in superconductorβ-Bi2Pd from the three-dimensional to the two-dimensional limit

“…The prediction and discovery of topological insulators (TIs) [1][2][3][4][5][6][7][8][9][10][11][12][13] have triggered the quest for other classes of materials that host exotic quantum states, such as topological superconductors [14][15][16] and Weyl [17][18][19][20][21], Dirac [22][23][24][25][26], and nodal-line [27,28] semimetals. Similar to TIs, topological superconductors (TSCs) are characterized by a full paring gap in the bulk and topologically protected gapless states on the edge or surface that can support massless Majorana fermions [14,15,[29][30][31].…”

Anomalous Hall Effect and Topological Defects in Antiferromagnetic Weyl Semimetals: Mn3Sn/Ge

“…In the 1980s, topology entered with the discovery of the quantum Hall effect. These ideas came together in the mid-2000s to unveil broad applications to electronic systems in the form of topological insulators, superconductors [3,4] and semimetals with topological Weyl (and other) fermion excitations [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The AHE re-appears as one of the key emergent properties of topological semimetals, and coming full circle, most ferromagnets are now believed to host Weyl fermions to which their AHE is at least in part attributed.…”