The observation of π-shifts in the Little-Parks effect in 4Hb-TaS 2

• Published in: Nature communications 2024-05, Vol.15 (1), p.4623
• Main Authors: Almoalem, Avior, Feldman, Irena, Mangel, Ilay, Shlafman, Michael, Yaish, Yuval E, Fischer, Mark H, Moshe, Michael, Ruhman, Jonathan, Kanigel, Amit
• Format: Article
• Language: English
• ISSN: 2041-1723
• DOI: 10.1038/s41467-024-48260-x

Finding evidence of non-trivial pairing states is one of the greatest experimental challenges in the field of unconventional superconductivity. Such evidence requires phase-sensitive probes susceptible to the internal structure of the order parameter. We report the measurement of the Little-Parks effect in the unconventional superconductor candidate 4Hb-TaS . In half of our rings, which are fabricated from single-crystals, we find a π-shift in the transition-temperature oscillations. According to theory, such a π-shift is only possible if the order parameter is non-s-wave. In the absence of crystallographic defects, the shift provides evidence of a multi-component order parameter. Thus, this observation increases the likelihood of the two-component order parameter scenario in 4Hb-TaS . Furthermore, we show that T is enhanced as a function of the out-of-plane field when a constant in-plane field is applied, which we explain using a two-component order-parameter.