Searcharxiv⌕ Search

arXiv subjects

Baokai Wang

Publications and source records attributed to Baokai Wang.

22 records · Page 2Linked to original sources
arXiv2018

Observation of topological nodal-loop state in RAs3 (R = Ca, Sr)

Topological nodal-line semimetals (NLSs) are unique materials, which harbor one-dimensional line nodes along with the so-called drumhead surface states arising from nearly dispersionless two dimensional surface bands. However, a direct observation of these drumhead surface states in the currently realized NLSs has remained elusive. Here, by using high-resolution angle-resolved photoemission spectroscopy (ARPES) along with parallel first principles calculations, we examine the topological characteristics of SrAs3 and CaAs3. SrAs3 is found to show the presence of a topological nodal-loop, while CaAs3 is found to lie near a topologically trivial phase. Our analysis reveals that the surface projections of the bulk nodal-points in SrAs3 are connected by drumhead surface states. Notably, the topological states in SrAs3 and CaAs3 are well separated from other irrelevant bands in the vicinity of the Fermi level. These compounds thus provide a hydrogen-like simple platform for developing an in-depth understanding of the quantum phase transitions of NLSs.

cond-mat.mes-hall↗
arXiv2017

Topological Hopf and chain link semimetal states and their application to Co2MnGa (Theory and Materials Prediction)

Topological semimetals can be classified by the connectivity and dimensionality of the band cross- ing in momentum space. The band crossings of a Dirac, Weyl, or an unconventional fermion semimet- al are 0D points, whereas the band crossings of a nodal-line semimetal are 1D closed loops. Here we propose that the presence of perpendicular crystalline mirror planes can protect 3D band crossings characterized by nontrivial links such as a Hopf link or a coupled-chain, giving rise to a variety of new types of topological semimetals. We show that the nontrivial winding number protects topolog- ical surface states distinct from those in previously known topological semimetals with a vanishing spin-orbit interaction. We also show that these nontrivial links can be engineered by tuning the mirror eigenvalues associated with the perpendicular mirror planes. Using first-principles band structure calculations, we predict the ferromagnetic full Heusler compound Co2MnGa as a candidate. Both Hopf link and chain-like bulk band crossings and unconventional topological surface states are identified.

cond-mat.mes-hall↗
arXiv2015

Fermi arc topology and interconnectivity in Weyl fermion semimetals TaAs, TaP, NbAs, and NbP

The family of binary compounds including TaAs, TaP, NbAs, and NbP was recently discovered as the first realization of Weyl semimetals. In order to develop a comprehensive description of the charge carriers in these Weyl semimetals, we performed systematic electronic structure calculations which reveal the nature of Fermi surfaces and their complex interconnectivity in TaAs, TaP, NbAs, and NbP. Our work report the first comparative and comprehensive study of Fermi surface topology and band structure details of all known members of the Weyl semimetal family and provide the necessary building blocks for advancing our understanding of their unique topologically protected low-energy Weyl fermion physics.

cond-mat.mes-hall↗