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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

(a) Temperature dependence of the bilayer resistance. At 7.1 K, the sharp transition was observed as in the inset. (b) Schematic illustrations for the current flowing condition above 7.1 K (top) and below 7.1 K (bottom).
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f2: (a) Temperature dependence of the bilayer resistance. At 7.1 K, the sharp transition was observed as in the inset. (b) Schematic illustrations for the current flowing condition above 7.1 K (top) and below 7.1 K (bottom).

Mentions: To evaluate the transport property of the prepared film, we first measured the temperature dependence of the resistance for the Cu/Nb bilayer by using the probe configuration shown in Fig. 2(b). Here, the measurement was performed by the current-bias lock-in technique with the current amplitude of 180 μA. As shown in Fig. 2(a), the resistance shows a typical normal conducting (NC) behavior with the residual resistance ratio of 3.2 above 7.1 K and becomes the zero-resistive superconducting state below 7.1 K. These characteristics indicate that the current flows mainly in the Cu film above 7.1 K and the current flows in the superconducting (SC) Nb film below 7.1 K, as schematically shown in Fig. 2(b). The transition temperature higher than the typical values in the patterned Nb thin films and the abrupt resistance change at 7.1 K indicate that the Nb layer has great performances as the superconductor33.


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)

(a) Temperature dependence of the bilayer resistance. At 7.1 K, the sharp transition was observed as in the inset. (b) Schematic illustrations for the current flowing condition above 7.1 K (top) and below 7.1 K (bottom).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: (a) Temperature dependence of the bilayer resistance. At 7.1 K, the sharp transition was observed as in the inset. (b) Schematic illustrations for the current flowing condition above 7.1 K (top) and below 7.1 K (bottom).
Mentions: To evaluate the transport property of the prepared film, we first measured the temperature dependence of the resistance for the Cu/Nb bilayer by using the probe configuration shown in Fig. 2(b). Here, the measurement was performed by the current-bias lock-in technique with the current amplitude of 180 μA. As shown in Fig. 2(a), the resistance shows a typical normal conducting (NC) behavior with the residual resistance ratio of 3.2 above 7.1 K and becomes the zero-resistive superconducting state below 7.1 K. These characteristics indicate that the current flows mainly in the Cu film above 7.1 K and the current flows in the superconducting (SC) Nb film below 7.1 K, as schematically shown in Fig. 2(b). The transition temperature higher than the typical values in the patterned Nb thin films and the abrupt resistance change at 7.1 K indicate that the Nb layer has great performances as the superconductor33.

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