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

Abstract

Majorana zero modes form as intrinsic defects in an odd-orbital one-dimensional superconductor thus motivating the search for such materials in the pursuit of Majorana physics. Here, we present combined experimental results and first principles calculations which suggest that quasi-one-dimensional K${}_2$Cr${}_3$As${}_3$ may be such a superconductor. Using inelastic neutron scattering we probe the dynamic spin-susceptibilities of K${}_2$Cr${}_3$As${}_3$ and K${}_2$Mo${}_3$As${}_3$ and show the presence of antiferromagnetic spin-fluctuations in both compounds. Below the superconducting transition, these fluctuations gap in K${}_2$Mo${}_3$As${}_3$ but not in K${}_2$Cr${}_3$As${}_3$. Using first principles calculations, we show that these fluctuations likely arise from nesting on one dimensional features of the Fermi surface. Considering these results we propose that while K${}_2$Mo${}_3$As${}_3$ is a conventional superconductor, K${}_2$Cr${}_3$As${}_3$ is likely a spin-triplet, and consequently, topological superconductor.

8 pages, 4 figures

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Cited by in corpus (5)

• Theoretical study of dynamical and electronic properties of noncentrosymmetric superconductor NbReSi
• Correlation stabilized ferromagnetic MnRuAs with distorted kagome lattice
• Emergent ferromagnetic ladder excitations in heavy fermion superconductor CeSb${}_2$
• The pairing symmetry in quasi-one-dimensional superconductor Rb2Mo3As3
• Multiple phases in K2Cr3As3: a playground for manipulating topological superconductivity