Signatures of the spin-triplet current in a Josephson spin valve: A micromagnetic analysis

Signatures of the spin-triplet current in a Josephson spin valve: A micromagnetic analysis A Josephson spin valve is a ferromagnetic spin valve sandwiched between two superconducting electrodes. It has been predicted theoretically that such a device may exhibit a long-range proximity effect due to generation of unconventional odd-frequency spin-triplet and long-range spin-singlet components of the supercurrent. In this work we present a comprehensive numerical analysis of Josephson spin-valve characteristics. Our analysis is based on micromagnetic simulations for Ni-based spin valves. The supercurrent through the spin valve depends on shapes and sizes of components, the magnetic domain structure, and the flux quantization. For very small monodomain spin valves, the triplet current is manifested by a dissimilar double maximum in the magnetic field dependence of the critical current Ic(H). However, this feature is washed away in larger devices due to appearance of domains and flux quantization. The only remaining signature of the triplet current in this case are beatings in Ic(H) with a half-flux quantum periodicity. The complexity of the device can make it difficult to identify the spin-triplet supercurrent without a detailed knowledge of the spin-valve state. However, we argue that unambiguous conclusions can be made from a systematic analysis of size, thickness, and shape dependencies of the Josephson spin-valve characteristics. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physical Review B American Physical Society (APS)

Signatures of the spin-triplet current in a Josephson spin valve: A micromagnetic analysis

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Signatures of the spin-triplet current in a Josephson spin valve: A micromagnetic analysis

Abstract

A Josephson spin valve is a ferromagnetic spin valve sandwiched between two superconducting electrodes. It has been predicted theoretically that such a device may exhibit a long-range proximity effect due to generation of unconventional odd-frequency spin-triplet and long-range spin-singlet components of the supercurrent. In this work we present a comprehensive numerical analysis of Josephson spin-valve characteristics. Our analysis is based on micromagnetic simulations for Ni-based spin valves. The supercurrent through the spin valve depends on shapes and sizes of components, the magnetic domain structure, and the flux quantization. For very small monodomain spin valves, the triplet current is manifested by a dissimilar double maximum in the magnetic field dependence of the critical current Ic(H). However, this feature is washed away in larger devices due to appearance of domains and flux quantization. The only remaining signature of the triplet current in this case are beatings in Ic(H) with a half-flux quantum periodicity. The complexity of the device can make it difficult to identify the spin-triplet supercurrent without a detailed knowledge of the spin-valve state. However, we argue that unambiguous conclusions can be made from a systematic analysis of size, thickness, and shape dependencies of the Josephson spin-valve characteristics.
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Publisher
The American Physical Society
Copyright
Copyright © ©2017 American Physical Society
ISSN
1098-0121
eISSN
1550-235X
D.O.I.
10.1103/PhysRevB.96.014511
Publisher site
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Abstract

A Josephson spin valve is a ferromagnetic spin valve sandwiched between two superconducting electrodes. It has been predicted theoretically that such a device may exhibit a long-range proximity effect due to generation of unconventional odd-frequency spin-triplet and long-range spin-singlet components of the supercurrent. In this work we present a comprehensive numerical analysis of Josephson spin-valve characteristics. Our analysis is based on micromagnetic simulations for Ni-based spin valves. The supercurrent through the spin valve depends on shapes and sizes of components, the magnetic domain structure, and the flux quantization. For very small monodomain spin valves, the triplet current is manifested by a dissimilar double maximum in the magnetic field dependence of the critical current Ic(H). However, this feature is washed away in larger devices due to appearance of domains and flux quantization. The only remaining signature of the triplet current in this case are beatings in Ic(H) with a half-flux quantum periodicity. The complexity of the device can make it difficult to identify the spin-triplet supercurrent without a detailed knowledge of the spin-valve state. However, we argue that unambiguous conclusions can be made from a systematic analysis of size, thickness, and shape dependencies of the Josephson spin-valve characteristics.

Journal

Physical Review BAmerican Physical Society (APS)

Published: Jul 18, 2017

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