Three-dimensional Critical Dirac semimetal in KMgBi

Surface Bogoliubov-Dirac cones and helical Majorana hinge modes in superconducting Dirac semimetals

In the presence of certain symmetries, three-dimensional Dirac semimetals can harbor not only surface Fermi arcs, but also surface Dirac cones. Motivated by the experimental observation of rotation-symmetry-protected Dirac semimetal states in iron-based superconductors, we investigate the potential intrinsic topological phases in a $C_{4z}$-rotational invariant superconducting Dirac semimetal with $s_{\pm}$-wave pairing. When the normal state harbors only surface Fermi arcs on the side surfaces, we find that an interesting gapped superconducting state with a quartet of Bogoliubov-Dirac cones o…

Observation of superconductivity in 3D Dirac semimetal Cd3As2 crystal

Lately, the three-dimensional (3D) Dirac semimetal, which possesses 3D linear dispersion in electronic structure as a bulk analogue of graphene, has generated widespread interests in both material science and condensed matter physics. Very recently, crystalline Cd3As2 has been proposed and proved to be one of 3D Dirac semimetals which can survive in atmosphere. Here, by controlled point contact (PC) measurement, we observe the exotic superconductivity around point contact region on the surface of Cd3As2 crystal. The observation of zero bias conductance peak (ZBCP) and double conductance peaks …

Topological superconductivity in Dirac semimetals

Dirac semimetals host bulk band-touching Dirac points and a surface Fermi loop. We develop a theory of superconducting Dirac semimetals. Establishing a relation between the Dirac points and the surface Fermi loop, we clarify how the nontrivial topology of Dirac semimetals affects their superconducting state. We note that the unique orbital texture of Dirac points and a structural phase transition of the crystal favor symmetry-protected topological superconductivity with a quartet of surface Majorana fermions. We suggest possible application of our theory to recently discovered superconducting …

Odd-frequency Berezinskii superconductivity in Dirac semimetals

We formulate a general framework for addressing both odd- and even-frequency superconductivity in Dirac semimetals and demonstrate that the odd-frequency or the Berezinskii pairing can naturally appear in these materials because of the chirality degree of freedom. We show that repulsive frequency-dependent interactions favor the Berezinskii pairing while an attractive electron-electron interaction allows for the BCS pairing. In the case of compensated Dirac and Weyl semimetals, both the conventional BCS and odd-frequency Berezinskii pairings require critical coupling. Since these pairings coul…

单轴应变下拓扑狄拉克半金属态产生的马约拉纳零能模的观测

Observation of Majorana zero modes emerged from topological Dirac semimetal states under uniaxial strain

本研究利用原位单轴应变装置在LiFeAs的拓扑狄拉克半金属体态中诱导出马约拉纳零能模，通过扫描隧道显微镜观测到相关涡旋束缚态演化，为铁基超导体中的马约拉纳物理调控提供了可控方法与新见解。

源自C6对称狄拉克半金属的节点高阶拓扑超导性

Nodal higher-order topological superconductivity from C6-symmetric Dirac semimetals

该研究针对C6对称半填充狄拉克半金属的节点超导态展开，发现BdG狄拉克点可产生高阶拓扑狄拉克超导态，并借助磁性拓扑量子化学理论证明其可通过BdG狄拉克点的相对拓扑指示。