Journal of Physical Studies 2(2), 278–282 (1998) DOI: https://doi.org/10.30970/jps.02.278 CRITICAL FIELDS OF A FERROMAGNETIC SUPERCONDUCTOR AT LOW TEMPERATURES

F. Clarysse, J. O. Indekeu
Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven,
Celestijnenlaan 200D, B-3001 Leuven, Belgium
E-mail: francis.clarysse@fys.kuleuven.ac.be

We present the calculation of the phase diagram of a ferromagnetic superconductor at very low temperatures. Although the materials under consideration are all type–II superconductors, a typical type–I behavior is predicted. We demonstrate that the term of fourth order in the magnetization in the Ginzburg–Landau expansion for the magnetic subsystem has to be taken into account in order to obtain the correct result for the critical field $H_c$. Furthermore, we discuss the computation of the critical field $H_{c2}$ and the surface nucleation field $H_{c3}$ for various surfaces.

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