Nonmonotonic critical temperature in superconductor/ferromagnet bilayers

By Y. Fominov, N. Chtchelkatchev, A. Golubov. 2002

151 citations recorded by the source corpus.

The critical temperature Tc of a superconductor/ferromagnet (SF) bilayer can exhibit nonmonotonic dependence on the thickness df of the F layer. SF systems have been studied for a long time; according to the experimental situation, a ?dirty? limit is often considered which implies that the mean free path in the layers is the second smallest spatial scale after the Fermi wavelength. However, all calculations reported for the dirty limit were done with some additional assumptions, which can be violated in actual experiments. Therefore, we develop a general method (to be exact, two independent methods) for investigating Tc as a function of the bilayer parameters in the dirty case. Comparing our theory with experiment, we obtain good agreement. In the general case, we observe three characteristic types of Tc(df) behavior: (1) a nonmonotonic decay of Tc to a finite value exhibiting a minimum at particular df; (2) a reentrant behavior, characterized by a vanishing of Tc in a certain interval of df and finite values otherwise; and (3) a monotonic decay of Tc and a vanishing at finite df. Qualitatively, the nonmonotonic behavior of Tc(df) is explained by the interference of quasiparticles in the F layer, which can be either constructive or destructive depending on the value of df.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics

View Paper: https://www.semanticscholar.org/paper/d72d59953eda480ce6da995f0857df98c454ae4c

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In Atomic and Molecular Physics, and Optics

1. J. Linder
2. J. Robinson
3. A. Buzdin
4. F. Bergeret
5. A. Volkov
6. V. Ryazanov
7. K. Efetov

In Condensed Matter Physics

1. J. Linder
2. F. Bergeret
3. K. Efetov
4. A. Volkov
5. J. Robinson
6. A. Buzdin
7. V. Ryazanov
8. Alexander V. Balatsky

Citations in the corpus

• Proximity effect in superconductor-ferromagnet heterostructures (2005, background): “Theoretical fit (Fominov et al., 2002) gives the exchange field value h ∼ 130 K and the interface transparency parameter γB ∼ 0.3.”
• Odd triplet superconductivity and related phenomena in superconductor-ferromagnet structures (2005, background): “…calculated in many works (Bagrets et al., 2003; Baladie and Buzdin, 2003; Baladie et al., 2001; Buzdin and Kupriyanov, 1991; Demler et al., 1997; Fominov et al., 2002, 2003; Khusainov and Proshin, 1997; Proshin et al., 2001; Proshin and Khusainov, 1998, 1999; Radovic et al., 1991; Tagirov,…”
• Superconducting spintronics (2015, background): “The strong oscillatory dependence of Tc on dF may be understood in terms of quasiparticle interference inside the ferromagnetic region [60].”