A magnetic excitation linking quasi-1D Chevrel-type selenide and arsenide superconductors

Logan M. Whitt; Tyra C. Douglas; Songxue Chi; Keith M. Taddei; Jared M. Allred

doi:10.1103/PhysRevMaterials.6.124804

paper

A magnetic excitation linking quasi-1D Chevrel-type selenide and arsenide superconductors

arXiv:2110.10226 · doi:10.1103/PhysRevMaterials.6.124804

Abstract

The quasi-one-dimensional Chevrel phases, A $_{2}$ Mo $_{6}$ Se $_{6}$ (A = Tl, In, K, Rb, Cs), are of interest due to their atypical electronic properties. The Tl and In analogues undergo a superconducting transition whereas the alkali metal analogues show charge gapping of another, not well understood type. We report the results of inelastic neutron scattering on polycrystalline In $_{2}$ Mo $_{6}$ Se $_{6}$ ( $T_{c} = 2.85$ K) and Rb $_{2}$ Mo $_{6}$ Se $_{6}$ (non-superconducting) samples, which reveal a column of intensity with linear dispersion from [0 0 1/2] to [0 0 1] in both compounds. The observed temperature and | $Q$ | independence together suggest the presence of unconventional carriers with a spin contribution to the excitation. This is contrary to the prevailing model for these materials, which is that they are non-magnetic. The excitation has similar dispersion and $S (Q, E, T)$ behavior as one observed in the structurally related superconducting compounds A $_{2}$ Cr $_{3}$ As $_{3}$ and A $_{2}$ Mo $_{3}$ As $_{3}$ (A = K, Rb, Cs), which has been interpreted as magnetic in origin and related to Fermi surface nesting. The connection is unexpected because the calculated Fermi surface of the arsenides differs substantially from the A $_{2}$ Mo $_{6}$ Se $_{6}$ compounds, and many consider them distinct classes of materials. The new observation suggests a hidden link in the physics between both classes of superconductors, perhaps originating from their quasi-low-dimensional character.

Replaced with accepted article: 12 pages, 3 figures. Appendix: 4 pages, 1 figure

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Cited by in corpus (1)

Gapless spin-excitations in the superconducting state of a quasi-one-dimensional spin-triplet superconductor