Three-dimensional doped Dirac insulators foster simply connected (in both topological and trivial regimes) and annular (deep inside the topological regime) Fermi surfaces (FSs) in the normal state, and allow on-site repulsions among fermions with opposite spin ($U_1$) and parity ($U_2$) eigenvalues. From an unbiased leading-order (one-loop) renormalization group analysis, controlled by a suitable $ε$ expansion, we show that this system develops a strong propensity toward the nucleation of scalar $s$-wave and odd-parity pseudoscalar $p$-wave pairings, favored by repulsive $U_1$ and $U_2$ interactions, respectively, irrespective of the underlying FS topology. Our results can be pertinent for the observed superconductivity in various doped narrow gap semiconductors, and the theoretical foundation can readily be applied to investigate similar phenomenon in various doped topological materials.
Visualizing superconductivity in an inversion-symmetry-broken doped Weyl semimetal
外尔半金属MoTe $_2$为研究外尔物理和超导性之间的相互作用提供了一个难得的机会。最近的研究发现，Se的掺杂可以提高超导体的超导电性，但抑制了Weyl态出现所必需的Td结构相。到目前为止，还没有建立一个微观的理解可能共存的增强超导性和Td相。本文利用扫描隧道显微镜（STM）研究了一种最佳掺杂的新型超导体MoTe $_{1.85}$ Se $_{0.15}$，其体相温度为1.5K。利用准粒子干涉成像技术，我们确定了超导体整体共存的反转对称性破缺的低温Td相的存在。一致地，我们发现从上临界场和涡旋附近态密度的衰减中提取的超导相干长度远大于现有的掺杂剂引起的化学无序的特征长度尺度。我们发现MoTe $_{1.85}$ Se $_{0.15}$中的Weyl半金属正常相具有强的超导电性，这使其成为实现拓扑超导电性的一个有希望的候选者。
