A Proximity Effect in Pure HTS/Ferromagnet Contacts

• Published in: IEEE transactions on applied superconductivity Vol. 26; no. 3; pp. 1 - 5
• Main Authors: Khusainov, Mansur G., Khusainov, Marat M., Sakhratov, Yury A., Matukhin, Vadim L., Proshin, Yurii N.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Charge carrier processes; High-temperature superconductors; Magnetism; multilayers; Nanostructures; proximity effect; Proximity effects; Superconducting magnets; Superconducting transition temperature; superconductivity; superconductivity; Magnetism; multilayers; superconducting transition temperature; proximity effect
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2016.2529286

The proximity effect is theoretically studied for thin and massive pure ferromagnet/high-temperature superconductor (F/HTS) contacts. It is shown that there is no continuous matching between the s-wave and d-wave pair amplitudes at the HTS/F boundary. In thin HTS/F nanostructures, the exchange field strongly suppresses the averaged sand d-pairing and leads to the competition between BCS and FFLO scenarios of superconductivity. On the contrary, in massive HTS/F contact, the exchange field has no effect on the critical temperature T c d of d-wave pairing. This is due to the lack of d-wave pairing in F layers, resulting in full internal reflection of d-wave pairs even from the perfectly transparent HTS/F boundary. The s-wave superconductivity localized at the HTS/F interface is predicted.Spontaneous symmetry change of the order parameter at the HTS/F interfaces from initially d-wave type to s-type becomes possible for massive HTS/F contact. It qualitatively agrees with experimental observations of the mixture of sand d-wave components at the Ag/BiSrCaCuO and Fe/Ag/BiSrCaCuO interfaces.