Magnetic and superconducting phase diagram of Nb/Gd/Nb trilayers

Yu N. Khaydukov*, A. S. Vasenko, E. A. Kravtsov, V. V. Progliado, V. D. Zhaketov, A. Csik, Yu V. Nikitenko, A. V. Petrenko, T. Keller, A. A. Golubov, M. Yu Kupriyanov, A.V. Ustinov, V. L. Aksenov, B. Keimer

*Corresponding author for this work

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Abstract

We report on a study of the structural, magnetic, and superconducting properties of Nb(25nm)/Gd(df)/Nb(25nm) hybrid structures of a superconductor/ ferromagnet (S/F) type. The structural characterization of the samples, including careful determination of the layer thickness, was performed using neutron and x-ray scattering with the aid of depth-sensitive mass spectrometry. The magnetization of the samples was determined by superconducting quantum interference device magnetometry and polarized neutron reflectometry, and the presence of magnetic ordering for all samples down to the thinnest Gd(0.8 nm) layer was shown. The analysis of the neutron spin asymmetry allowed us to prove the absence of magnetically dead layers in junctions with Gd interlayer thickness larger than one monolayer. The measured dependence of the superconducting transition temperature Tc(df) has a damped oscillatory behavior with well-defined positions of the minimum at df=3 nm and the following maximum at df=4 nm, in qualitative agreement with prior work [J. S. Jiang et al., Phys. Rev. B 54, 6119 (1996)PRBMDO0163-182910.1103/PhysRevB.54.6119]. We use a theoretical approach based on the Usadel equations to analyze the experimental Tc(df) dependence. The analysis shows that the observed minimum at df=3 nm can be described by the so-called zero to π phase transitions of highly transparent S/F interfaces with a superconducting correlation length ξf≈4 nm in Gd. This penetration length is several times higher than for strong ferromagnets like Fe, Co, and Ni, thus simplifying the preparation of S/F structures with df∼ξf which are of topical interest in superconducting spintronics.

Original languageEnglish
Article number144511
Number of pages8
JournalPhysical review B: Covering condensed matter and materials physics
Volume97
Issue number14
DOIs
Publication statusPublished - 13 Apr 2018

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Superconducting materials
Phase diagrams
Neutrons
phase diagrams
neutrons
Magnetization
Magnetoelectronics
hybrid structures
SQUIDs
x ray scattering
Superconducting transition temperature
magnetic measurement
Mass spectrometry
interlayers
Monolayers
mass spectroscopy
penetration
Phase transitions
transition temperature
asymmetry

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Khaydukov, Y. N., Vasenko, A. S., Kravtsov, E. A., Progliado, V. V., Zhaketov, V. D., Csik, A., ... Keimer, B. (2018). Magnetic and superconducting phase diagram of Nb/Gd/Nb trilayers. Physical review B: Covering condensed matter and materials physics, 97(14), [144511]. https://doi.org/10.1103/PhysRevB.97.144511
Khaydukov, Yu N. ; Vasenko, A. S. ; Kravtsov, E. A. ; Progliado, V. V. ; Zhaketov, V. D. ; Csik, A. ; Nikitenko, Yu V. ; Petrenko, A. V. ; Keller, T. ; Golubov, A. A. ; Kupriyanov, M. Yu ; Ustinov, A.V. ; Aksenov, V. L. ; Keimer, B. / Magnetic and superconducting phase diagram of Nb/Gd/Nb trilayers. In: Physical review B: Covering condensed matter and materials physics. 2018 ; Vol. 97, No. 14.
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abstract = "We report on a study of the structural, magnetic, and superconducting properties of Nb(25nm)/Gd(df)/Nb(25nm) hybrid structures of a superconductor/ ferromagnet (S/F) type. The structural characterization of the samples, including careful determination of the layer thickness, was performed using neutron and x-ray scattering with the aid of depth-sensitive mass spectrometry. The magnetization of the samples was determined by superconducting quantum interference device magnetometry and polarized neutron reflectometry, and the presence of magnetic ordering for all samples down to the thinnest Gd(0.8 nm) layer was shown. The analysis of the neutron spin asymmetry allowed us to prove the absence of magnetically dead layers in junctions with Gd interlayer thickness larger than one monolayer. The measured dependence of the superconducting transition temperature Tc(df) has a damped oscillatory behavior with well-defined positions of the minimum at df=3 nm and the following maximum at df=4 nm, in qualitative agreement with prior work [J. S. Jiang et al., Phys. Rev. B 54, 6119 (1996)PRBMDO0163-182910.1103/PhysRevB.54.6119]. We use a theoretical approach based on the Usadel equations to analyze the experimental Tc(df) dependence. The analysis shows that the observed minimum at df=3 nm can be described by the so-called zero to π phase transitions of highly transparent S/F interfaces with a superconducting correlation length ξf≈4 nm in Gd. This penetration length is several times higher than for strong ferromagnets like Fe, Co, and Ni, thus simplifying the preparation of S/F structures with df∼ξf which are of topical interest in superconducting spintronics.",
author = "Khaydukov, {Yu N.} and Vasenko, {A. S.} and Kravtsov, {E. A.} and Progliado, {V. V.} and Zhaketov, {V. D.} and A. Csik and Nikitenko, {Yu V.} and Petrenko, {A. V.} and T. Keller and Golubov, {A. A.} and Kupriyanov, {M. Yu} and A.V. Ustinov and Aksenov, {V. L.} and B. Keimer",
year = "2018",
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Khaydukov, YN, Vasenko, AS, Kravtsov, EA, Progliado, VV, Zhaketov, VD, Csik, A, Nikitenko, YV, Petrenko, AV, Keller, T, Golubov, AA, Kupriyanov, MY, Ustinov, AV, Aksenov, VL & Keimer, B 2018, 'Magnetic and superconducting phase diagram of Nb/Gd/Nb trilayers', Physical review B: Covering condensed matter and materials physics, vol. 97, no. 14, 144511. https://doi.org/10.1103/PhysRevB.97.144511

Magnetic and superconducting phase diagram of Nb/Gd/Nb trilayers. / Khaydukov, Yu N.; Vasenko, A. S.; Kravtsov, E. A.; Progliado, V. V.; Zhaketov, V. D.; Csik, A.; Nikitenko, Yu V.; Petrenko, A. V.; Keller, T.; Golubov, A. A.; Kupriyanov, M. Yu; Ustinov, A.V.; Aksenov, V. L.; Keimer, B.

In: Physical review B: Covering condensed matter and materials physics, Vol. 97, No. 14, 144511, 13.04.2018.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Magnetic and superconducting phase diagram of Nb/Gd/Nb trilayers

AU - Khaydukov, Yu N.

AU - Vasenko, A. S.

AU - Kravtsov, E. A.

AU - Progliado, V. V.

AU - Zhaketov, V. D.

AU - Csik, A.

AU - Nikitenko, Yu V.

AU - Petrenko, A. V.

AU - Keller, T.

AU - Golubov, A. A.

AU - Kupriyanov, M. Yu

AU - Ustinov, A.V.

AU - Aksenov, V. L.

AU - Keimer, B.

PY - 2018/4/13

Y1 - 2018/4/13

N2 - We report on a study of the structural, magnetic, and superconducting properties of Nb(25nm)/Gd(df)/Nb(25nm) hybrid structures of a superconductor/ ferromagnet (S/F) type. The structural characterization of the samples, including careful determination of the layer thickness, was performed using neutron and x-ray scattering with the aid of depth-sensitive mass spectrometry. The magnetization of the samples was determined by superconducting quantum interference device magnetometry and polarized neutron reflectometry, and the presence of magnetic ordering for all samples down to the thinnest Gd(0.8 nm) layer was shown. The analysis of the neutron spin asymmetry allowed us to prove the absence of magnetically dead layers in junctions with Gd interlayer thickness larger than one monolayer. The measured dependence of the superconducting transition temperature Tc(df) has a damped oscillatory behavior with well-defined positions of the minimum at df=3 nm and the following maximum at df=4 nm, in qualitative agreement with prior work [J. S. Jiang et al., Phys. Rev. B 54, 6119 (1996)PRBMDO0163-182910.1103/PhysRevB.54.6119]. We use a theoretical approach based on the Usadel equations to analyze the experimental Tc(df) dependence. The analysis shows that the observed minimum at df=3 nm can be described by the so-called zero to π phase transitions of highly transparent S/F interfaces with a superconducting correlation length ξf≈4 nm in Gd. This penetration length is several times higher than for strong ferromagnets like Fe, Co, and Ni, thus simplifying the preparation of S/F structures with df∼ξf which are of topical interest in superconducting spintronics.

AB - We report on a study of the structural, magnetic, and superconducting properties of Nb(25nm)/Gd(df)/Nb(25nm) hybrid structures of a superconductor/ ferromagnet (S/F) type. The structural characterization of the samples, including careful determination of the layer thickness, was performed using neutron and x-ray scattering with the aid of depth-sensitive mass spectrometry. The magnetization of the samples was determined by superconducting quantum interference device magnetometry and polarized neutron reflectometry, and the presence of magnetic ordering for all samples down to the thinnest Gd(0.8 nm) layer was shown. The analysis of the neutron spin asymmetry allowed us to prove the absence of magnetically dead layers in junctions with Gd interlayer thickness larger than one monolayer. The measured dependence of the superconducting transition temperature Tc(df) has a damped oscillatory behavior with well-defined positions of the minimum at df=3 nm and the following maximum at df=4 nm, in qualitative agreement with prior work [J. S. Jiang et al., Phys. Rev. B 54, 6119 (1996)PRBMDO0163-182910.1103/PhysRevB.54.6119]. We use a theoretical approach based on the Usadel equations to analyze the experimental Tc(df) dependence. The analysis shows that the observed minimum at df=3 nm can be described by the so-called zero to π phase transitions of highly transparent S/F interfaces with a superconducting correlation length ξf≈4 nm in Gd. This penetration length is several times higher than for strong ferromagnets like Fe, Co, and Ni, thus simplifying the preparation of S/F structures with df∼ξf which are of topical interest in superconducting spintronics.

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DO - 10.1103/PhysRevB.97.144511

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