Mathematical modeling of temperature dependence of the second critical field of thin films of niobium nitride
N. D. Kuzmichev1, M. A. Vasyutin2, E. A. Lapshina3, D. A. Shilkin4
| Annotation | Temperature dependence of the second critical field $H_{c2}(T)$ for superconductors due to different values of Maki parameter and of spin-orbit scattering parameter is modeled mathematically within the framework of WHH-theory (Werthamer, Helfand, Hohenberg). Temperature dependencies of superconducting transition for the first harmonic of voltage of thin niobium nitride (NbN) films are investigated in dc magnetic fields up to 8 T. By approximating experimental temperature dependence of the upper critical field of NbN films by theoretical dependence $H_{c2}(T)$ Maki parameter is obtained, that takes into account the spin paramagnetism effect in this material. From transport and optical measurements done in this and other studies the most important parameters of NbN superconductor are evaluated that are consistent with the data of present work. |
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| Keywords | WHH theory, second critical field, niobium nitride, spin paramagnetism, Ginsburg–Landau coherence length, Maki parameter, spin-orbit scattering parameter, Ioffe–Regel parameter |
1N. D. Kuzmichev (Professor, Head of General ScientificDisciplines Department, RuzaevkaEngineering Institute (branch), Ogarev Mordovia State University, Saransk; kuzmichevnd@yandex.ru)
2M. A. Vasyutin (Associate professor of General ScientificDisciplines Department, RuzaevkaEngineering Institute (branch), Ogarev Mordovia State University, Saransk; vasyutinm@mail.ru)
3E. A. Lapshina (Associate professor of General ScientificDisciplines Department, RuzaevkaEngineering Institute (branch), Ogarev Mordovia State University, Saransk; e.lapshina2010@yandex.ru)
4D. A. Shilkin (Postgraduate student of General Scientific Disciplines Department, Ruzaevka Engineering Institute (branch), Ogarev Mordovia State University, Saransk; dwi8hi@outlook.com)
Citation: N. D. Kuzmichev, M. A. Vasyutin, E. A. Lapshina, D. A. Shilkin, "[Mathematical modeling of temperature dependence of the second critical field of thin films of niobium nitride]", Zhurnal Srednevolzhskogo matematicheskogo obshchestva,18:4 (2016) 134–142 (In Russian)
