Nb/Gd/Nb Trilayers for π-Junction applications: Growth and Characterization
ORAL
Abstract
Nb/Gd/Nb Trilayers for π-Junction applications: growth and characterization
D. Korucu, Reza Loloee, Norman O. Birge
Dept. of Physics and Astronomy
Michigan State University
Josephson π-junctions have been proposed as circuit elements for digital superconducting logic [1]. Such π-junctions can be realized by inserting a thin ferromagnetic layer into the junction; however the resulting stray magnetic fields may be detrimental to circuit performance. Using a rare-Earth/transition metal ferrimagnetic alloy such as GdxCo1-x near its compensation point avoids that issue, but the short mean free path of the alloy causes the supercurrent to decay rapidly with GdCo thickness [2]. Instead, we are pursuing Gd/Co bilayers, which are coupled antiferromagnetically. A first step is to explore the properties of Josephson junctions containing Gd alone. Previous work [3] has shown that Nb/Gd interfaces are highly transparent; however, nano-scale JJs with Gd have not yet been reported.
Magnetic characterization of Nb/Gd/Nb trilayers indicate that the Gd is strongly affected by contact with Nb. By inserting buffer layers of Au or Pt between the Nb and Gd, however, the Gd saturation magnetization increases and the coercivity decreases dramatically. Studies of Josephson junctions containing the Gd surrounded by buffer layers are in progress.
[1] A. Mitrovic and M. Bocko, Phys. Rev. Applied 23, 067001 (2025).
[2] A. E. Madden, PhD thesis, Michigan State Univ. (2022).
[3] Y. N. Khaydukov et al., Phys. Rev. B 97, 144511 (2018).
D. Korucu, Reza Loloee, Norman O. Birge
Dept. of Physics and Astronomy
Michigan State University
Josephson π-junctions have been proposed as circuit elements for digital superconducting logic [1]. Such π-junctions can be realized by inserting a thin ferromagnetic layer into the junction; however the resulting stray magnetic fields may be detrimental to circuit performance. Using a rare-Earth/transition metal ferrimagnetic alloy such as GdxCo1-x near its compensation point avoids that issue, but the short mean free path of the alloy causes the supercurrent to decay rapidly with GdCo thickness [2]. Instead, we are pursuing Gd/Co bilayers, which are coupled antiferromagnetically. A first step is to explore the properties of Josephson junctions containing Gd alone. Previous work [3] has shown that Nb/Gd interfaces are highly transparent; however, nano-scale JJs with Gd have not yet been reported.
Magnetic characterization of Nb/Gd/Nb trilayers indicate that the Gd is strongly affected by contact with Nb. By inserting buffer layers of Au or Pt between the Nb and Gd, however, the Gd saturation magnetization increases and the coercivity decreases dramatically. Studies of Josephson junctions containing the Gd surrounded by buffer layers are in progress.
[1] A. Mitrovic and M. Bocko, Phys. Rev. Applied 23, 067001 (2025).
[2] A. E. Madden, PhD thesis, Michigan State Univ. (2022).
[3] Y. N. Khaydukov et al., Phys. Rev. B 97, 144511 (2018).
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Presenters
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Demet Korucu
- Michigan State University