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Competition between Pi-coupling and FFLO modulation in SF/SF atomic thickness bilayers

S. Tollis·J. Cayssol·A. Buzdin
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Abstract

We present the detailed theoretical study of a heterostructure comprising of two coupled ferromagnetic superconducting layers. Our model may be also applicable to the layered superconductors with alternating interlayer coupling in a parallel magnetic field. It is demonstrated that such systems exhibit a competition between the nonuniform Larkin-Ovchinnikov-Fulde-Ferrel (FFLO) state and the superconducting state where the sign of the superconducting order parameter is opposite in adjacent layers. We determine the complete temperature-field phase diagram both in the cases of low and strong interlayer coupling. In the former we obtain a new Pi-phase inserted within the FFLO phase and located close to the usual tricritical point, whereas in the latter the bilayer in the state reveals a very high paramagnetic limit and the phenomenon of field-induced superconductivity.

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S. Tollis, J. Cayssol, A. Buzdin. 2005-09-23. Competition between Pi-coupling and FFLO modulation in SF/SF atomic thickness bilayers. https://arxiv.org/abs/cond-mat/0509599

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