Two-dimensional oxide topological insulator with iron-pnictide superconductor LiFeAs structure

Abstract

By using first-principles calculations, we propose that ZrSiO can be looked as a three-dimensional (3D) oxide weak topological insulator (TI) and its single layer is a long-sought-after 2D oxide TI with a band gap up to 30 meV. Calculated phonon spectrum of the single layer ZrSiO indicates it is dynamically stable and the experimental achievements in growing oxides with atomic precision ensure that it can be readily synthesized. This will lead to novel devices based on TIs, the so called "topotronic" devices, operating under room-temperature and stable when exposed in the air. Thus, a new field of "topotronics" will arise. Another intriguing thing is this oxide 2D TI has the similar crystal structure as the well-known iron-pnictide superconductor LiFeAs. This brings great promise in realizing the combination of superconductor and TI, paving the way to various extraordinary quantum phenomena, such as topological superconductor and Majorana modes. We further find that there are many other isostructural compounds hosting the similar electronic structure and forming a W HM -family with W being Zr, Hf or La, H being group IV or group V element, and M being group VI one.

Nearly massless Dirac fermions and strong Zeeman splitting in the nodal-line semimetal ZrSiS probed by de Haas–van Alphen quantum oscillations

“…The 3D FS is also likely the cause of the "butterfly-shaped" anisotropic angular-dependence of magnetoresistance [51][52]71] seen in ZrSiS. By substituting Te for S, thereby reducing the dimensionality [43], such "butterfly-shaped" anisotropy evolves to a simple two-fold anisotropy expected for a 2D system [71].…”

“…1a) are not only bonded to neighboring S and Si layers within the slab, but also bonded to S atoms in the adjacent slabs (see Fig. 1a) [43,48]. The 3D FS is also likely the cause of the "butterfly-shaped" anisotropic angular-dependence of magnetoresistance [51][52]71] seen in ZrSiS.…”

“…Among these materials, ZrSiS, which possesses layered tetragonal structure (see Fig. 1a) [43,45,48], shows distinct properties.…”

“…In addition to the aforementioned topological semimetals with discrete Dirac/Weyl nodes, a new type of topological semimetal with Dirac bands crossing along a one-dimensional line in momentum space has also been predicted [35][36][37][38][39][40][41][42][43] and experimentally observed in several compounds such as PbTaSe 2 [44], ZrSiS [45][46], and PtSn 4 [47]. Among these materials, ZrSiS, which possesses layered tetragonal structure (see Fig.…”

Observation of open-orbit Fermi surface topology in the extremely large magnetoresistance semimetal MoAs2

“…Another two series of semimetals possessing quadratic XMR behavior and rich topological characteristics are the ZrSiS family [37][38][39] and LnX (Ln = La, Y, Nd, or Ce; X = Sb/Bi) series [40][41][42][43][44][45][46], whose electronic structures have been considerably studied both in theory and experiment [47][48][49][50][51][52][53]. While the band structures of the T mPn 2 series have been theoretically characterized in several work [32][33][34]54], experimental observations have not yet been reported.…”