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Significant change of spin transport property in Cu/Nb bilayer due to superconducting transition.

Ohnishi K, Ono Y, Nomura T, Kimura T - Sci Rep (2014)

Bottom Line: To observe such SC spin transports, the suppression of the extrinsic effects originating from the heating and Oersted field due to the electric current is a crucial role.Pure spin current without accompanying the charge current is known as a powerful mean for preventing such extrinsic effects.By using this ideal platform, we found that the spin absorption is strongly suppressed by the SC transition of Nb.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan [2] Research Center for Quantum Nano-Spin Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan.

ABSTRACT
The combination between the spin-dependent and super-conducting (SC) transports is expected to provide intriguing properties such as crossed Andreev reflection and spin-triplet superconductivity. This may be able to open a new avenue in the field of spintronics, namely superconducting spintronics because a superconductor itself has great potential for future nanoelectronic applications. To observe such SC spin transports, the suppression of the extrinsic effects originating from the heating and Oersted field due to the electric current is a crucial role. Pure spin current without accompanying the charge current is known as a powerful mean for preventing such extrinsic effects. However, non-negligible heat flow is found to exist even in a conventional pure spin current device based on laterally-configured spin valve because of the heating around the spin injector. Here, we develop a nanopillar-based lateral spin valve, which significantly reduces the heat generation, on a superconducting Nb film. By using this ideal platform, we found that the spin absorption is strongly suppressed by the SC transition of Nb. This demonstration is the clear evidence that the super-conducting Nb is an insulator for the pure spin current.

No MeSH data available.


Related in: MedlinePlus

Magnetic field dependence of the contact resistance of the Py1/Cu junction together with the probe configuration for this measurement.The insets show the schematic illustration of the conducting state in the Cu/Nb layer.
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f5: Magnetic field dependence of the contact resistance of the Py1/Cu junction together with the probe configuration for this measurement.The insets show the schematic illustration of the conducting state in the Cu/Nb layer.

Mentions: Finally, we focus on the spin transport in the Cu layer in which the Cooper pairs exist because of the proximity effect. Influence of the Cooper pair on the non-equilibrium spin accumulation was studied. Figure 5 shows the magnetic field dependence of the contact resistance for the Py1/Cu junction. The probe configuration for this measurement is shown in the inset. The small abrupt resistance changes in low magnetic field are due to the anisotropic magnetoresistance of the Py nanopillar. The gradual reversible resistance change below 100 mT can be understood by the field dependence of the resistance for the Cu layer. Owing to the proximity effect from the Nb, the current flowing around the Cu/Nb interface becomes the super current. As a result, the resistance of the Cu around the interface becomes zero in the absence of the magnetic field. However, the super current induced by the proximity effect is easily spoiled by applying the magnetic field. Thus, the gradual field dependence of the resistance is the evidence that Cooper pairs exist in the Cu channel. It should be noted that the field dependence of the nonlocal spin valve signal does not show such a gradual change. This indicates that the spin relaxation process in the Cu layer is not affected by the proximity effect from the superconductor.


Significant change of spin transport property in Cu/Nb bilayer due to superconducting transition.

Ohnishi K, Ono Y, Nomura T, Kimura T - Sci Rep (2014)

Magnetic field dependence of the contact resistance of the Py1/Cu junction together with the probe configuration for this measurement.The insets show the schematic illustration of the conducting state in the Cu/Nb layer.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4151101&req=5

f5: Magnetic field dependence of the contact resistance of the Py1/Cu junction together with the probe configuration for this measurement.The insets show the schematic illustration of the conducting state in the Cu/Nb layer.
Mentions: Finally, we focus on the spin transport in the Cu layer in which the Cooper pairs exist because of the proximity effect. Influence of the Cooper pair on the non-equilibrium spin accumulation was studied. Figure 5 shows the magnetic field dependence of the contact resistance for the Py1/Cu junction. The probe configuration for this measurement is shown in the inset. The small abrupt resistance changes in low magnetic field are due to the anisotropic magnetoresistance of the Py nanopillar. The gradual reversible resistance change below 100 mT can be understood by the field dependence of the resistance for the Cu layer. Owing to the proximity effect from the Nb, the current flowing around the Cu/Nb interface becomes the super current. As a result, the resistance of the Cu around the interface becomes zero in the absence of the magnetic field. However, the super current induced by the proximity effect is easily spoiled by applying the magnetic field. Thus, the gradual field dependence of the resistance is the evidence that Cooper pairs exist in the Cu channel. It should be noted that the field dependence of the nonlocal spin valve signal does not show such a gradual change. This indicates that the spin relaxation process in the Cu layer is not affected by the proximity effect from the superconductor.

Bottom Line: To observe such SC spin transports, the suppression of the extrinsic effects originating from the heating and Oersted field due to the electric current is a crucial role.Pure spin current without accompanying the charge current is known as a powerful mean for preventing such extrinsic effects.By using this ideal platform, we found that the spin absorption is strongly suppressed by the SC transition of Nb.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan [2] Research Center for Quantum Nano-Spin Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan.

ABSTRACT
The combination between the spin-dependent and super-conducting (SC) transports is expected to provide intriguing properties such as crossed Andreev reflection and spin-triplet superconductivity. This may be able to open a new avenue in the field of spintronics, namely superconducting spintronics because a superconductor itself has great potential for future nanoelectronic applications. To observe such SC spin transports, the suppression of the extrinsic effects originating from the heating and Oersted field due to the electric current is a crucial role. Pure spin current without accompanying the charge current is known as a powerful mean for preventing such extrinsic effects. However, non-negligible heat flow is found to exist even in a conventional pure spin current device based on laterally-configured spin valve because of the heating around the spin injector. Here, we develop a nanopillar-based lateral spin valve, which significantly reduces the heat generation, on a superconducting Nb film. By using this ideal platform, we found that the spin absorption is strongly suppressed by the SC transition of Nb. This demonstration is the clear evidence that the super-conducting Nb is an insulator for the pure spin current.

No MeSH data available.


Related in: MedlinePlus