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Beilstein J Nanotechnol. 2016 Jul 04;7:957-69. doi: 10.3762/bjnano.7.88. eCollection 2016.

Thickness dependence of the triplet spin-valve effect in superconductor-ferromagnet-ferromagnet heterostructures.

Beilstein journal of nanotechnology

Daniel Lenk, Vladimir I Zdravkov, Jan-Michael Kehrle, Günter Obermeier, Aladin Ullrich, Roman Morari, Hans-Albrecht Krug von Nidda, Claus Müller, Mikhail Yu Kupriyanov, Anatolie S Sidorenko, Siegfried Horn, Rafael G Deminov, Lenar R Tagirov, Reinhard Tidecks

Affiliations

  1. Institut für Physik, Universität Augsburg, Universitätsstraße 1, D-86159 Augsburg, Germany.
  2. Institut für Physik, Universität Augsburg, Universitätsstraße 1, D-86159 Augsburg, Germany; D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev, Moldova.
  3. Institut für Physik, Universität Augsburg, Universitätsstraße 1, D-86159 Augsburg, Germany; D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev, Moldova; Solid State Physics Department, Kazan Federal University, Kremlevskaya Str. 18, 420008 Kazan, Russian Federation.
  4. Solid State Physics Department, Kazan Federal University, Kremlevskaya Str. 18, 420008 Kazan, Russian Federation; Skobeltsyn Institute of Nuclear Physics, Moscow State University, Leninskie gory, GSP-1, Moscow 119992, Russia.
  5. D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev, Moldova.
  6. Solid State Physics Department, Kazan Federal University, Kremlevskaya Str. 18, 420008 Kazan, Russian Federation.
  7. Institut für Physik, Universität Augsburg, Universitätsstraße 1, D-86159 Augsburg, Germany; Solid State Physics Department, Kazan Federal University, Kremlevskaya Str. 18, 420008 Kazan, Russian Federation.

PMID: 27547613 PMCID: PMC4979884 DOI: 10.3762/bjnano.7.88

Abstract

BACKGROUND: In nanoscale layered S/F1/N/F2/AF heterostructures, the generation of a long-range, odd-in-frequency spin-projection one triplet component of superconductivity, arising at non-collinear alignment of the magnetizations of F1 and F2, exhausts the singlet state. This yields the possibility of a global minimum of the superconducting transition temperature T c, i.e., a superconducting triplet spin-valve effect, around mutually perpendicular alignment.

RESULTS: The superconducting triplet spin valve is realized with S = Nb a singlet superconductor, F1 = Cu41Ni59 and F2 = Co ferromagnetic metals, AF = CoO x an antiferromagnetic oxide, and N = nc-Nb a normal conducting (nc) non-magnetic metal, which serves to decouple F1 and F2. The non-collinear alignment of the magnetizations is obtained by applying an external magnetic field parallel to the layers of the heterostructure and exploiting the intrinsic perpendicular easy-axis of the magnetization of the Cu41Ni59 thin film in conjunction with the exchange bias between CoO x and Co. The magnetic configurations are confirmed by superconducting quantum interference device (SQUID) magnetic moment measurements. The triplet spin-valve effect has been investigated for different layer thicknesses, d F1, of F1 and was found to decay with increasing d F1. The data is described by an empirical model and, moreover, by calculations using the microscopic theory.

CONCLUSION: The long-range triplet component of superconducting pairing is generated from the singlet component mainly at the N/F2 interface, where the amplitude of the singlet component is suppressed exponentially with increasing distance d F1. The decay length of the empirical model is found to be comparable to twice the electron mean free path of F1 and, thus, to the decay length of the singlet component in F1. Moreover, the obtained data is in qualitative agreement with the microscopic theory, which, however, predicts a (not investigated) breakdown of the triplet spin-valve effect for d F1 smaller than 0.3 to 0.4 times the magnetic coherence length, ξF1.

Keywords: heterostructures; superconducting spin valve; thin films; triplet superconductivity

References

  1. Phys Rev Lett. 2002 Dec 23;89(26):267001 - PubMed
  2. Phys Rev Lett. 2003 Mar 21;90(11):117006 - PubMed
  3. Phys Rev Lett. 2010 Nov 12;105(20):207002 - PubMed
  4. Phys Rev Lett. 2011 Feb 11;106(6):067005 - PubMed
  5. Phys Rev Lett. 2010 Apr 2;104(13):137002 - PubMed
  6. Phys Rev B Condens Matter. 1995 Jun 1;51(22):15933-15941 - PubMed
  7. Phys Rev Lett. 2015 Aug 7;115(6):067201 - PubMed
  8. Phys Rev Lett. 2001 Apr 30;86(18):4096-9 - PubMed
  9. Phys Rev Lett. 2006 Aug 4;97(5):057004 - PubMed
  10. Phys Rev B Condens Matter. 1991 Oct 1;44(14):7585-7600 - PubMed
  11. Phys Rev Lett. 2006 Jan 27;96(3):037004 - PubMed
  12. Phys Rev Lett. 2009 Jul 10;103(2):027004 - PubMed
  13. Nat Commun. 2014;5:3048 - PubMed
  14. Phys Rev Lett. 2012 Aug 3;109(5):057005 - PubMed

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