Long-Range Spin-Polarized Quasiparticle Transport in Mesoscopic Al Superconductors with a Zeeman Splitting

Hübler, F.; Wolf, Michael; Beckmann, D.; Löhneysen, H. v.

doi:10.1103/physrevlett.109.207001

Cited by 99 publications

(137 citation statements)

References 21 publications

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“…A well-known application beyond the linear regime are normal-metal/insulator/superconductor (NIS) junctions under voltage bias close to the energy gap of the superconductor, which provide local electronic refrigeration [10–11]. Charge and spin transport in the nonlinear bias regime have also been investigated experimentally [8–9] and theoretically [19–23]. …”

Section: Introductionmentioning

confidence: 99%

Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions

Kolenda¹,

Machon²,

Beckmann³

et al. 2016

Beilstein J. Nanotechnol.

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Background: Thermoelectric effects result from the coupling of charge and heat transport and can be used for thermometry, cooling and harvesting of thermal energy. The microscopic origin of thermoelectric effects is a broken electron–hole symmetry, which is usually quite small in metal structures. In addition, thermoelectric effects decrease towards low temperatures, which usually makes them vanishingly small in metal nanostructures in the sub-Kelvin regime. Results: We report on a combined experimental and theoretical investigation of thermoelectric effects in superconductor/ferromagnet hybrid structures. We investigate the dependence of thermoelectric currents on the thermal excitation, as well as on the presence of a dc bias voltage across the junction. Conclusion: Large thermoelectric effects are observed in superconductor/ferromagnet and superconductor/normal-metal hybrid structures. The spin-independent signals observed under finite voltage bias are shown to be reciprocal to the physics of superconductor/normal-metal microrefrigerators. The spin-dependent thermoelectric signals in the linear regime are due to the coupling of spin and heat transport, and can be used to design more efficient refrigerators.

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Section: Introductionmentioning

confidence: 99%

Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions

Kolenda¹,

Machon²,

Beckmann³

et al. 2016

Beilstein J. Nanotechnol.

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“…In this paper, we summarize some of our recent experimental results on non-equilibrium charge and spin transport in nanoscale superconductors [12,17–18], and perform additional numerical analysis to obtain more insight into the physical mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Charge and spin transport in mesoscopic superconductors

Wolf

Hübler

Kolenda

et al. 2014

Beilstein J. Nanotechnol.

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Summary Background: Non-equilibrium charge transport in superconductors has been investigated intensely in the 1970s and 1980s, mostly in the vicinity of the critical temperature. Much less attention has been paid to low temperatures and the role of the quasiparticle spin. Results: We report here on nonlocal transport in superconductor hybrid structures at very low temperatures. By comparing the nonlocal conductance obtained by using ferromagnetic and normal-metal detectors, we discriminate charge and spin degrees of freedom. We observe spin injection and long-range transport of pure, chargeless spin currents in the regime of large Zeeman splitting. We elucidate charge and spin transport by comparison to theoretical models. Conclusion: The observed long-range chargeless spin transport opens a new path to manipulate and utilize the quasiparticle spin in superconductor nanostructures.

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“…The combination between the spin and super-conducting (SC) transports is also expected to provide intriguing transport properties, leading to an emerging field in spintronics because a superconductor itself has great potential for future nanoelectronic applications such as Josephson circuit and quantum computing910. Although a number of experimental studies have been performed1112131415161718192021, several intriguing phenomena suggested in theoretical study have not been demonstrated222324. Moreover, the experimental study on subgap transports such as a crossed Andreev reflection and a spin triplet proximity effect have still exciting topics in superconducting spintronics because of their fantastic properties2526272829.…”

mentioning

confidence: 99%

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

Ohnishi

Ono

Nomura

et al. 2014

Sci Rep

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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.

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Long-Range Spin-Polarized Quasiparticle Transport in Mesoscopic Al Superconductors with a Zeeman Splitting

Cited by 99 publications

References 21 publications

Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions

Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions

Charge and spin transport in mesoscopic superconductors

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

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