Two-component nematic superconductivity in 4Hb-TaS2

I Silber; S Mathimalar; I Mangel; A K Nayak; O Green; N Avraham; H Beidenkopf; I Feldman; A Kanigel; A Klein; M Goldstein; A Banerjee; E Sela; Y Dagan

doi:10.1038/s41467-024-45169-3

Two-component nematic superconductivity in 4Hb-TaS₂

Nat Commun. 2024 Jan 27;15(1):824. doi: 10.1038/s41467-024-45169-3.

Authors

I Silber¹, S Mathimalar², I Mangel³, A K Nayak², O Green¹, N Avraham², H Beidenkopf², I Feldman³, A Kanigel³, A Klein^{4

5}, M Goldstein¹, A Banerjee⁶, E Sela¹, Y Dagan⁷

Affiliations

¹ School of Physics and Astronomy, Tel - Aviv University, Tel Aviv, 69978, Israel.
² Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel.
³ Physics Department, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
⁴ Department of Physics, Faculty of Natural Sciences, Ariel University, Ariel, 40700, Israel.
⁵ Department of Chemical Physics, The Weizmann Institute of Science, Rehovot, 76100, Israel.
⁶ Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel.
⁷ School of Physics and Astronomy, Tel - Aviv University, Tel Aviv, 69978, Israel. yodagan@tauex.tau.ac.il.

Abstract

Most superconductors have an isotropic, single component order parameter and are well described by the standard (BCS) theory for superconductivity. Unconventional, multiple-component superconductors are exceptionally rare and are much less understood. Here, we combine scanning tunneling microscopy and angle-resolved macroscopic transport for studying the candidate chiral superconductor, 4Hb-TaS₂. We reveal quasi-periodic one-dimensional modulations in the tunneling conductance accompanied by two-fold symmetric superconducting critical field. The strong modulation of the in-plane critical field, H_c2, points to a nematic, unconventional order parameter. However, the imaged vortex core is isotropic at low temperatures. We suggest a model that reconciles this apparent discrepancy and takes into account previously observed spontaneous time-reversal symmetry breaking at low temperatures. The model describes a competition between a dominating chiral superconducting order parameter and a nematic one. The latter emerges close to the normal phase. Our results strongly support the existence of two-component superconductivity in 4Hb-TaS₂ and can provide valuable insights into other systems with coexistent charge order and superconductivity.