2017/03/24 by E F Talantsev, Evgeny Talantsev, W P Crump +8 · 53 citations
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Niobium #Penetration depth #Selenide #Superconducting coherence length #Superconductivity #Surface and Thin Film Phenomena #Tantalum #Topological Materials and Phenomena #Transition temperature #cond-mat.supr-con
paper · pdf · doi:10.1088/2053-1583/aa6917
published in 2D Materials 4(2), 025072 (IOP Publishing) · 43 pages, 12 figures
openalex publication_date 2017/03/24 · arxiv created 2017/03/29 · arxiv updated 2017/03/30 · openalex created_date 2017/04/07 · openalex updated_date 2026/08/05
Abstract Recent experiments showed that thinning gallium, iron selenide and 2H tantalum disulfide to single/several monoatomic layer(s) enhances their superconducting critical temperatures. Here, we characterize these superconductors by extracting the absolute values of the London penetration depth, the superconducting energy gap, and the relative jump in specific heat at the transition temperature from their self-field critical currents. Our central finding is that the enhancement in transition temperature for these materials arises from the opening of an additional superconducting gap, while retaining a largely unchanged ‘bulk’ superconducting gap. Literature data reveals that ultrathin niobium films similarly develop a second superconducting gap. Based on the available data, it seems that, for type-II superconductors, a new superconducting band appears when the film thickness becomes smaller than the out-of-plane coherence length. The same mechanism may also be the cause of enhanced interface superconductivity.