Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
Doi
Abstract
We report an unusual persistence of superconductivity against high magnetic fields in the iron-chalcogenide
film FeTe:Ox below ≈ 2.5 K. Instead of saturating like a mean-field behavior with a single order parameter, the
measured low-temperature upper critical field increases progressively, suggesting a large supply of superconducting
states accessible via magnetic field or low-energy thermal fluctuations. We demonstrate that superconducting
states of finite momenta can be realized within the conventional theory, despite its questionable
applicability. Our findings reveal a fundamental characteristic of superconductivity and electronic structure in
the strongly-correlated iron-based superconductors