Superconducting and ferromagnetic properties of NbN/NiCu and NbTiN/NiCu bilayer nanostructures for photon detection

Klimov, A.; Puniak, R.; Aichner, B.; Lang, W.; Joon, E.; Stern, R.; Slysz, W.; Guziewicz, M.; Juchniewicz, M.; Borysiewicz, M.A.; Kruszka, R.; Wgrzecki, M.; Laszcz, A.; Czerwinski, A. (2015). Superconducting and ferromagnetic properties of NbN/NiCu and NbTiN/NiCu bilayer nanostructures for photon detection. Proceedings of SPIE - The International Society for Optical Engineering, 9504. Spie - International Society For Optical Engineering, 950405.10.1117/12.2179697.
publitseeritud konverentsiettekanne
Klimov, A.; Puniak, R.; Aichner, B.; Lang, W.; Joon, E.; Stern, R.; Slysz, W.; Guziewicz, M.; Juchniewicz, M.; Borysiewicz, M.A.; Kruszka, R.; Wgrzecki, M.; Laszcz, A.; Czerwinski, A.
  • Inglise
Superconducting and ferromagnetic properties of NbN/NiCu and NbTiN/NiCu bilayer nanostructures for photon detection
Proceedings of SPIE - The International Society for Optical Engineering
Proceedings of SPIE - The International Society for Optical Engineering
Spie - International Society For Optical Engineering
0277-786X
9781628416251
9504
2015
950405
Ilmunud
1.1. Teadusartiklid, mis on kajastatud Web of Science andmebaasides Science Citation Index Expanded, Social Sciences Citation Index, Arts & Humanities Citation Index ja/või andmebaasis Scopus (v.a. kogumikud)
WOS

Viited terviktekstile

dx.doi.org/10.1117/12.2179697

Seotud asutused

Instytut Technologii Elektronowej; Institute of Physics of the Polish Academy of Sciences; Universitat Wien; National Institute of Chemical Physics and Biophysics, Tallinn; University of Rochester

Lisainfo

© 2015 COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. Performance of superconducting single-photon detectors based on resistive hotspot formation in nanostripes upon optical photon absorption depends strongly on the critical current density JC of the fabricated nanostructure. Utilization of an ultrathin, weak-ferromagnet cap layer on the top of a superconducting film enhances of the structure€™s JC due to an extra flux pinning. We have fabricated a number of both NbN/NiCu and NbTiN/NiCu superconductor/ferromagnet (S/F) ultrathin bilayers and microbridges. NbN and NbTiN underlayers with thicknesses varying from 4 to 7 nm were grown using dc-magnetron sputtering on chemically cleaned sapphire single-crystal substrates. After rapid thermal annealing at high temperatures, the S films were coated with Ni0.54Cu0.46 overlayers with thicknesses of about 6 nm, using cosputtering. Compositions of the deposited films were confirmed by EDX spectroscopy analysis, while TEM studies demonstrated excellent epitaxial quality of our S layers with ∼2-nm-thick F/S transition layer and atomically-sharp S/substrate interface. Magnetic properties of bilayers were studied using both the SQUID and Vibrating Sample Magnetometer techniques in low and high magnetic fields. Low-temperature tests confirmed that in all cases NiCu films were ferromagnetic with the Curie temperature of above 30 K. Below the bilayer critical temperature of approx. 12-13 K, the structures were fully proximitized with the strong superconducting signal. For superconducting transport properties characterization, we used bilayers patterned into 40-1/4m-long microbridges with the width varying from 0.4 1/4m to 2 1/4m. The same S/F nanostructures were also used to study their superconducting fluctuations. The temperature dependence of magnetoresistance demonstrated highly 2-dimensional character with an unusual negative region that extended almost to room temperature. In the S/F sample, the fluctuations were observed to be substantially below theoretical expectations.
2-dimensional superconductivity | Low temperature magnetic properties | NbN/NiCu | NbTiN/NiCu | Superconducting fluctiations | Superconductor/ferromagnet ultrathin bilayers