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HAIT Journal of Science and Engineering Volume 1, Issue 4, pp. 707-720 © 2004 Holon Academic Institute of Technology | |||||
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Anomalous behavior of the upper critical field due to energy dependent broadening of the Landau levels
Vladimir N. Zhuravlev1,2,* and Vladimir Shapiro1
1Research Center for Quantum Communication Engineering
| at Department of Communication Engineering, Holon Academic Institute of Technology, 52 Golomb Str., Holon 58102, Israel 2Chemistry Department, Technion - Israel Institute of Technology, Haifa 32000, Israel *Corresponding author: chrvlzh@techunix.technion.ac.il Received 2 November 2003, revised 28 June 2004, accepted 11 August 2004
| We suggest a new approach to the linearized gap equations in the BCS-theory which enable us to determine the upper critical field in the semi-classical approximation for the model electron energy spectrum. It is shown that for electron systems with relatively strong BCS coupling having the Landau level (LL) spectrum with the level width increasing far from the Fermi level, the upper critical field has anomalous upward curvature. We also discuss strong coupling for energy independent LL broadening. In this case form of the Hc2(T) curve is insignificantly different from that obtained in the Werthamer-Helfand-Hohenberg theory.
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