Reduced magnetic moment of the 3.86 µm thick In sample in perpendicular field, H ci is the critical field of the transition from the intermediate to the normal state. The green line represents M calculated from the model. The nonlocal effect is the only phenomenon steaming immediately from a finite size of Cooper pairs. Predicted in 1953, it was for the first time measured in this project with In and Sn samples This allowed us to determined directly the size of Copper pairs, the mass of the pairs, and the London penetration depth characterizing the number density of Cooper pairs. Owing to that we were able to solve the most long standing superconductivity problem, the problem of the intermediate state (IS), put forward by F. London, Peierls and Landau in the 1930s. A new theoretical model of the IS, consistently addressing all thermodynamic properties of the IS, was developed and experimentally verified (see highlights of ). In this year development the IS model was completed. Now the model also addresses the DC magnetic moment M, the hallmark of superconductivity and one of the most important sample characteristics, which was well understood only for samples with zero demagnetizing factor. Our model completely solves the problem of the IS providing important new insights in magnetic properties of all, type-I and type-II, superconductors. The only “weak link” of our model is oversimplified approximation of the field distribution near the sample surface. This year we also performed preliminary measurements of the field distribution near the sample surface outside the sample and of the domain’s shape inside the sample in the IS, using low-energy muon spin rotation spectroscopy. It turned out that reality is radically different from what was expected from the theoretical calculations. The field lines exiting the sample instead of diverging (as predicted by Landau) converge before they finally relax to the uniform field distribution far away from the sample. On the other hand the width of the normal domains near the surface shrinks instead of predicted widening, as it is shown in the bottom figure. This is explained by the gain in condensation energy due to increasing volume of the superconducting phase. Publications: (1) V. Kozhevnikov, R. Wijngaarden, J. de Wit, C. Van Haesendonck, PRB 89, (R) (2014); (2) V. Kozhevnikov and C. Van Haesendonck, under review. 1/2 N NN SS Cross sectional view of the magnetic field distribution and of the domain shape measured with the same indium sample in the intermediate state at the applied field higher than half of H ci. N (S) indicates the normal (superconducting) phase. Nonlocal effect and microscopic parameters in superconductors Vladimir Kozhevnikov, Tulsa Community College, DMR

Students of TCC Special topics in physics class (left to right) James Presley, Caleb Lear, Robert Acree and Ted Massad near their poster presented at the Oklahoma Research Day conference, University of Central Oklahoma, Tulsa Community College is a two-years college of primary high education. TCC students involved in the project take a class “Selected topics in physics”. The class meets once a week; each meeting students make presentations on a foremost topic of physics staying beyond the standard curriculum of college physics classes. Students completed the class have their tuition reimbursed from the grant. The most active students participate in the neutron’s experiments in Chalk River Laboratories, Canada, and in the muon’s experiments in Paul Scherrer Institute, Switzerland. The students take part at the APS March Meetings, and at the Oklahoma Research Day conferences held at the University of Central Oklahoma. As of today (August/2014) the class has been offered for seven semesters; total 25 students graduated the class. One former student is currently a graduate student in the physics department of the University of Tulsa; others continue their education in STEM specialties at universities of Oklahoma and elsewhere. Nonlocal effect and microscopic parameters in superconductors Vladimir Kozhevnikov,Tulsa Community College, DMR