2012/12/07 by V. Kozhevnikov, V. F. Kozhevnikov, Kozhevnikov, V. +7
Engineering · Physics and Astronomy · #FOS: Physical sciences #Magnetic properties of thin films #Magneto-Optical Properties and Applications #Physics of Superconductivity and Magnetism #Superconductivity (cond-mat.supr-con) #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.1212.1705
5 pages, 5 figures
openalex publication_date 2012/12/07 · arxiv created 2013/10/18 · arxiv updated 2013/10/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
To address unsolved fundamental problems of the intermediate state (IS), the equilibrium magnetic flux structure and the critical field in a high purity type-I superconductor (indium film) are investigated using magneto-optical imaging with a 3D vector magnet and electrical transport measurements. The least expected observation is that the critical field in the IS can be as small as nearly 40% of the thermodynamic critical field Hc. This indicates that the flux density in the bulk of normal domains can be considerably less than Hc, in apparent contradiction with the long established paradigm, stating that the normal phase is unstable below Hc. Here we present a novel theoretical model consistently describing this and all other properties of the IS. Moreover, our model, based the rigorous thermodynamic treatment of observed laminar flux structure in a tilted field, allows for a quantitative determination of the domain-wall parameter and the coherence length, and provides new insight into the properties of all superconductors.