Anisotropic fully-gapped superconductivity in quasi-one-dimensional Li$_{0.9}$Mo$_6$O$_{17}$

M. J. Grant; T. M. Huijbregts; R. Nicholls; M. Greenblatt; P. Chudzinski; A. Carrington; N. E. Hussey

paper

Anisotropic fully-gapped superconductivity in quasi-one-dimensional Li $_{0.9}$ Mo $_{6}$ O $_{17}$

arXiv:2602.19724

Abstract

Superconductivity in quasi-one-dimensional Li $_{0.9}$ Mo $_{6}$ O $_{17}$ emerges from an exotic, non-metallic normal state that exhibits signatures of Tomonaga-Luttinger liquid behavior, emergent symmetry and excitonic order. The high upper critical field, $H_{c 2}$ , in Li $_{0.9}$ Mo $_{6}$ O $_{17}$ suggests that that the favored pairing state is spin-triplet in nature. Here, we report measurements of the magnetic penetration depth down to $0.08 K$ ( $T / T_{c} ≲ 0.04$ ) and the specific heat down to $0.4 K$ ( $T / T_{c} ≲ 0.2$ ), and show that they are consistent with a moderately-coupled, fully-gapped superconducting state with marked gap anisotropy and a minimum ( $Δ_{min} ≃ 0.4 k_{B} T_{c}$ ) occurring over a very narrow region in $k$ -space. Combined with knowledge of $H_{c 2}$ , these measurements support the presence of a nodeless and possibly odd-parity spin-triplet superconducting order parameter in Li $_{0.9}$ Mo $_{6}$ O $_{17}$ .

13 pages, 5 figures

Anisotropic fully-gapped superconductivity in quasi-one-dimensional Li0.9​Mo6​O17​

Abstract

Anisotropic fully-gapped superconductivity in quasi-one-dimensional Li $_{0.9}$ Mo $_{6}$ O $_{17}$