Electronic structure and signature of Tomonaga-Luttinger liquid state in epitaxial CoSb1-x nanoribbons

Recently, monolayer CoSb/SrTiO3 has been proposed as a candidate harboring interfacial superconductivity in analogy with monolayer FeSe/SrTiO3. Experimentally, while the CoSb-based compounds manifesting as nanowires and thin films have been realized on SrTiO3 substrates, serving as a rich playground, their electronic structures are still unknown and yet to be resolved. Here, we have fabricated CoSb1-x nanoribbons with quasi-one-dimensional stripes on SrTiO3 (001) substrates using molecular beam epitaxy and investigated the electronic structure by in situ angle-resolved photoemission spectroscopy. Straight Fermi surfaces without lateral dispersions are observed. CoSb1-x/SrTiO3 is slightly hole doped, where the interfacial charge transfer is opposite to that in monolayer FeSe/SrTiO3. The spectral weight near the Fermi level exhibits power-law-like suppression and obeys a universal temperature scaling, serving as the signature of Tomonaga-Luttinger liquid (TLL) state. The obtained TLL parameter of similar to 0.21 shows the underlying strong correlations. Our results not only suggest CoSb(1-x )nanoribbon as a representative TLL system but also provide dues for further investigations on the CoSb-related interface.