Superconductivity in the nonsymmorphic line-nodal compound CaSb$_2$

Fermiology of a topological line-nodal compound CaSb2 and its implication to superconductivity: angle-resolved photoemission study

We performed angle-resolved photoemission spectroscopy with micro-focused beam on a topological line-nodal compound CaSb2 which undergoes a superconducting transition at the onset Tc~1.8 K, to clarify the Fermi-surface topology relevant to the occurrence of superconductivity. We found that a three-dimensional hole pocket at the G point is commonly seen for two types of single-crystalline samples fabricated by different growth conditions. On the other hand, the carrier-doping level estimated from the position of the chemical potential was found to be sensitive to the sample fabrication conditio…

Superconductivity and Quantum Oscillations in Single Crystals of the Compensated Semimetal CaSb$_{2}$

Bulk superconductivity in a topological semimetal is a first step towards realizing topological superconductors, which can host Majorana fermions allowing us to achieve quantum computing. Here, we report superconductivity and compensation of electrons and holes in single crystals of the nodal-line semimetal CaSb$_2$. We characterize the superconducting state and find that Cooper pairs have moderate-weak coupling, and the superconducting transition in specific heat down to 0.22 K deviates from that of a BCS superconductor. The non-saturating magnetoresistance and electron-hole compensation at l…

非对称超导体LaNiGa$_2$中含节点结构的费米学研究：一项德哈斯-范阿尔芬研究

Fermiology with nodal structures in nonsymmorphic superconductor LaNiGa$_2$: A de Haas-van Alphen study

本研究通过dHvA光谱与第一性原理计算，揭示非对称超导体LaNiGa$_2$的费米学特征，验证其晶格对称性及费米能级处的四重简并节点结构，证实其为原型拓扑晶体超导体，凸显节点准粒子对非常规超导配对的潜在作用。

Superconducting ground state of nonsymmorphic superconducting compound Zr$_{2}$Ir

The nonsymmorphic Zr$_{2}$Ir alloy is a possible topological semimetal candidate material and as such may be part of an exotic class of superconductors. Zr$_{2}$Ir is a superconductor with a transition temperature of 7.4 K with critical fields of 19.6(3) mT and 3.79(3) T, as determined by heat capacity and magnetisation. Zero field muon spin relaxation measurements show that time-reversal symmetry is preserved in these materials. The specific heat and transverse field muon spin rotation measurements rule out any possibility to have a nodal or anisotropic superconducting gap, revealing a conven…

棱柱狄拉克链使非对称性硅化物实现内在拓扑超导性

Hourglass Dirac chains enable intrinsic topological superconductivity in nonsymmorphic silicides

TaPtSi通过非对称性对称性实现内在拓扑超导性，其棱柱狄拉克链拓扑与非对称三重态配对相互作用，揭示了等原子硅化物作为统一材料平台的潜力。

在破缺时间反演对称性的超导体 LaNiGa$_2$ 中观测到对称性强制的费米面简并

Symmetry Enforced Fermi Surface Degeneracies Observed in Time-Reversal Symmetry-Breaking Superconductor LaNiGa$_2$

本研究利用 ARPES 测量 LaNiGa$_2$ 三维布里渊区电子结构，结合 DFT 证实了 Cmcm 空间群预言的费米面对称性强制简并及偶然近简并。

Vacancy-Engineered Flat-Band Superconductivity in Holey Graphene

A bipartite lattice with chiral symmetry is known to host zero energy flat bands if the numbers of the two sublattices are different. We demonstrate that this mechanism of producing flat bands can be realized on graphene by introducing periodic vacancies. Using first-principle calculations, we elaborate that even though the pristine graphene does not exactly preserve chiral symmetry, this mechanism applied to holey graphene still produces single or multiple bands as narrow as ~0.5eV near the Fermi surface throughout the entire Brillouin zone. Moreover, this mechanism can combine with vacancy-e…

C掺杂拓扑节线半金属Zr$_5$Pt$_3$中的电子-声子超导性：一项μ子自旋旋转与弛豫（$μ$SR）研究

Electron-phonon superconductivity in C-doped topological nodal-line semimetal Zr$_5$Pt$_3$: A muon spin rotation and relaxation ($μ$SR) study

本文结合磁化、$μ$SR实验与DFT计算，证明C掺杂Zr$_5$Pt$_3$是具有非点式Dirac节线态的电子-声子超导体，并揭示其常规$s$波超导及拓扑能带保护特征。