Experimental evidence of hourglass fermion in the candidate nonsymmorphic topological insulator KHgSb
نویسندگان
چکیده
Topological insulators (TIs) host novel states of quantum matter characterized by nontrivial conducting boundary states connecting valence and conduction bulk bands. All TIs discovered experimentally so far rely on either time-reversal or mirror crystal symmorphic symmetry to protect massless Dirac-like boundary states. Several materials were recently proposed to be TIs with nonsymmorphic symmetry, where a glide mirror protects exotic surface fermions with hourglass-shaped dispersion. However, an experimental confirmation of this new fermion is missing. Using angle-resolved photoemission spectroscopy, we provide experimental evidence of hourglass fermions on the (010) surface of crystalline KHgSb, whereas the (001) surface has no boundary state, in agreement with first-principles calculations. Our study will stimulate further research activities of topological properties of nonsymmorphic materials.
منابع مشابه
Topological insulators in ternary compounds with a honeycomb lattice.
We investigate a new class of ternary materials such as LiAuSe and KHgSb with a honeycomb structure in Au-Se and Hg-Sb layers. We demonstrate the band inversion in these materials similar to HgTe, which is a strong precondition for existence of the topological surface states. In contrast with graphene, these materials exhibit strong spin-orbit coupling and a small direct band gap at the Γ point...
متن کاملJ an 1 99 7 Experimental evidence of a metal - insulator transition in a half - filled Landau level
We have measured the low-temperature transport properties of a high-mobility front-gated GaAs/Al 0.33 Ga 0.67 As heterostructure. By changing the applied gate voltage, we can vary the amount of disorder within the system. At a Landau level filling factor ν = 1/2, where the system can be described by the composite fermion picture, we observe a crossover from metallic to insulating behaviour as t...
متن کاملChern insulator with large Chern numbers. Chiral Majorana fermion liquid
In the framework ofHofstadter’s approachwe provide a detailed analysis of a realization of exotic topological states such as the Chern insulator (CI)with largeChern numbers. In a transverse homogeneousmagnetic field a one-particle spectrumof fermions transforms to an intricate spectrum with afine topological structure of the subbands. In aweakmagnetic fieldH for a rationalmagnetic flux, a topol...
متن کاملSpacetime as a topological insulator: mechanism for the origin of the fermion generations.
We suggest a mechanism whereby the three generations of quarks and leptons correspond to surface modes in a five-dimensional theory. These modes arise from a nonlinear fermion dispersion relation in the extra dimension, much in the same manner as fermion surface modes in a topological insulator or lattice implementation of domain wall fermions. We also show that the topological properties can p...
متن کاملUnconventional superconductivity on a topological insulator.
We study proximity-induced superconductivity on the surface of a topological insulator (TI), focusing on unconventional pairing. We find that the excitation spectrum becomes gapless for any spin-triplet pairing, such that both subgap bound states and Andreev reflection is strongly suppressed. For spin-singlet pairing, the zero-energy surface state in the d(xy)-wave case becomes a Majorana fermi...
متن کامل