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Supercurrent enhancement in Bloch domain walls.
J W A Robinson1, F Chiodi, M Egilmez
1Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom. jjr33@cam.ac.uk
Scientific Reports
|September 29, 2012
Summary
Superconductivity research reveals how magnetic domain walls in nickel-gadolinium-nickel nanopillars influence supercurrents. Manipulating the domain wall state modifies the conversion of spin-singlet to spin-triplet Cooper pairs, impacting junction performance.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Superconductivity
Background:
- Ferromagnetic Josephson junctions exhibit spin-singlet to spin-triplet Cooper pair conversion.
- Magnetic inhomogeneity at superconductor/ferromagnet interfaces drives this triplet proximity effect.
- Isolating and utilizing magnetic domain walls (DW) for supercurrents remains challenging.
Purpose of the Study:
- Investigate supercurrents in magnetic Ni-Gd-Ni nanopillars.
- Explore the influence of tunable magnetic domain walls on superconductivity.
- Understand the mechanism of spin-triplet proximity effect in engineered magnetic structures.
Main Methods:
- Fabrication of Ni-Gd-Ni nanopillars.
- Field annealing at room temperature to modify the low-temperature domain wall state in Gadolinium.
- Measurement of supercurrents at 4.2 K.
Main Results:
- Demonstrated supercurrents through Ni-Gd-Ni nanopillars.
- Field annealing significantly altered the low-temperature domain wall state.
- Observed a striking effect of the modified domain wall state on junction supercurrent.
- The efficiency of singlet-triplet pair interconversion was found to depend on magnetic helicity.
Conclusions:
- The observed supercurrent modulation is explained by the interconversion of spin-singlet and spin-triplet Cooper pairs.
- The magnetic helicity of the structure plays a crucial role in the efficiency of this interconversion.
- Field-tuneable Bloch domain walls in Gd offer a pathway to control triplet proximity effects in Josephson junctions.
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