RESUMO
Dirac and Weyl semimetals host exotic quasiparticles with unconventional transport properties, such as high magnetoresistance and carrier mobility. Recent years have witnessed a huge number of newly predicted topological semimetals from existing databases; however, experimental verification often lags behind such predictions. Common reasons are synthetic difficulties or the stability of predicted phases. Here, we report the synthesis of the type-II Dirac semimetal Ir2In8S, an air-stable compound with a new structure type. This material has two Dirac crossings in its electronic structure along the Γ-Z direction of the Brillouin zone. We further show that Ir2In8S has a high electron carrier mobility of â¼10â¯000 cm2/(V s) at 1.8 K and a large, nonsaturating transverse magnetoresistance of â¼6000% at 3.34 K in a 14 T applied field. Shubnikov de-Haas oscillations reveal several small Fermi pockets and the possibility of a nontrivial Berry phase. With its facile crystal growth, novel structure type, and striking electronic structure, Ir2In8S introduces a new material system to study topological semimetals and enable advances in the field of topological materials.
RESUMO
The family of transition-metal dipnictides has been of theoretical and experimental interest because this family hosts topological states and extremely large magnetoresistance (MR). Recently,TaAs2, a member of this family, has been predicted to support a topological crystalline insulating state. Here, by using high-resolution angle-resolved photoemission spectroscopy (ARPES), we reveal both closed and open pockets in the metallic Fermi surface (FS) and linearly dispersive bands on the (2â¾01) surface, along with the presence of extreme MR observed from magneto-transport measurements. A comparison of the ARPES results with first-principles computations shows that the linearly dispersive bands on the measured surface ofTaAs2are trivial bulk bands. The absence of symmetry-protected surface state on the (2â¾01) surface indicates its topologically dark nature. The presence of open FS features suggests that the open-orbit fermiology could contribute to the extremely large MR ofTaAs2.
RESUMO
The electronic properties of the heavy metal superconductor [Formula: see text] are reported. The estimated superconducting parameters obtained from physical properties measurements indicate that [Formula: see text] is a BCS-type superconductor. Electronic band structure calculations show that Ir d-states dominate the Fermi level. A comparison of electronic band structures of [Formula: see text] and [Formula: see text] shows that the Ir-compound has a strong spin-orbit-coupling effect, which creates a complex Fermi surface.