Quasiparticle-mediated spin Hall effect in a superconductor

Wakamura, Taro; Akaike, Hiroyuki; Omori, Yasutomo; Niimi, Yasuhiro; Takahashi, Saburo; Fujimaki, Akira; Maekawa, Sadamichi; Otani, Y.

doi:10.1038/nmat4276

Cited by 100 publications

(123 citation statements)

References 29 publications

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“…As reported in an s -wave superconductor NbN 3 , thermally-excited quasiparticles can produce ISHE voltage in the superconducting state, although further experimental verification in other s -wave superconductors seems necessary 1 . In our case, however, ISHE mediated by quasiparticles does not explain the oscillations, since the YBCO length along the voltage contacts is much greater than the charge imbalance length, the length scale where the spin-polarized quasiparticle currents relax into the Cooper-pair condensates 3 . Also, the quasiparticle scenario does not explain the presence of the onset temperature of the oscillations (~30 K), which is much lower than T C .…”

Section: Resultsmentioning

confidence: 95%

“…The singlet-triplet conversion of paring amplitudes at the interfaces offers tantalizing possibilities for superconducting spintronics devices in which Joule heating and dissipation are minimized 2 . Also, it was recently reported that thermally-excited quasiparticles, superpositions of electron-like and hole-like excitation with spin-1/2, exhibit a giant spin Hall effect by electric spin injection into an s -wave superconductor NbN 3 .…”

Section: Introductionmentioning

confidence: 99%

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Oscillatory Nernst effect in Pt|ferrite|cuprate-superconductor trilayer films

Shiomi

Lustikova

Saitoh

2017

Sci Rep

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Although magnetism and superconductivity hardly coexist in a single material, recent advances in nanotechnology and spintronics have brought to light their interplay in magnetotransport in thin-film heterostructures. Here, we found a periodic oscillation of Nernst voltage with respect to magnetic fields in Pt|LiFe5O8 (Pt|LFO) bilayers grown on a cuprate superconductor YBa2Cu3O7−x (YBCO). At high temperatures above the superconducting transition temperature (T C) of YBCO, spin Seebeck voltages originating in Pt|LFO layers are observed. As temperature decreases well below T C, the spin Seebeck voltage is suppressed and unconventional periodic voltage oscillation as a function of magnetic fields appears; such an oscillation emerging along the Hall direction in the superconducting state has not been observed yet. Dynamics of superconducting vortices pinned by surface precipitates seems responsible for the oscillatory Nernst effect.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Oscillatory Nernst effect in Pt|ferrite|cuprate-superconductor trilayer films

Shiomi

Lustikova

Saitoh

2017

Sci Rep

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“…The fact that there is a giant enhancement in the spin Hall angle for quasiparticles with energies around the gap is consistent with the main findings of Refs. [25,26]. We provide microscopic expressions for the density of states in the superconductor with respect to its normal-state value N S ( ) and the scattering times in Eq.…”

Section: -3mentioning

confidence: 99%

“…Moreover, these studies indicated that the magnitudes of the skew scattering and the side-jump contributions are renormalized by different amounts below the superconducting critical temperature in spin Hall devices. Recent nonlocal measurements found an inverse spin Hall signal that is 2000 times stronger in the superconducting state compared to the normal state [26].…”

Section: Introductionmentioning

confidence: 99%

Spin Hall effect and spin swapping in diffusive superconductors

Espedal¹,

Lange²,

Sadjina³

et al. 2017

Phys. Rev. B

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We consider the spin-orbit-induced spin Hall effect and spin swapping in diffusive superconductors. By employing the nonequilibrium Keldysh Green's function technique in the quasiclassical approximation, we derive coupled transport equations for the spectral spin and particle distributions and for the energy density in the elastic scattering regime. We compute four contributions to the spin Hall conductivity, namely, skew scattering, side jump, anomalous velocity, and the Yafet contribution. The reduced density of states in the superconductor causes a renormalization of the spin Hall angle. We demonstrate that all four of these contributions to the spin Hall conductivity are renormalized in the same way in the superconducting state. In its simplest manifestation, spin swapping transforms a primary spin current into a secondary spin current with swapped current and polarization directions. We find that the spin-swapping coefficient is not explicitly but only implicitly affected by the superconducting gap through the renormalized diffusion coefficients. We discuss experimental consequences for measurements of the (inverse) spin Hall effect and spin swapping in four-terminal geometries. In our geometry, below the superconducting transition temperature, the spin-swapping signal is increased an order of magnitude while changes in the (inverse) spin Hall signal are moderate.

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“…Refs. [30][31][32][33][34][35] considered out-of-equilibrium situations, in which quasiparticle effects give rise to spin (charge) currents as a result of charge (spin) injection. In particular, Ref.…”

Section: Introductionmentioning

confidence: 99%

Direct and inverse superspin Hall effect in two-dimensional systems: Electrical detection of spin supercurrents

Risinggård

Linder

2019

Phys. Rev. B

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A useful experimental signature of the ordinary spin Hall effect is the spin accumulation it produces at the sample edges. The superspin Hall current [Phys. Rev. B 96, 094512 (2017)] is a transverse equilibrium spin current which is induced by a charge supercurrent. We study the superspin Hall current numerically, and find that it does not give rise to a similar edge magnetization. We also predict and numerically confirm the existence of the inverse superspin Hall effect, which produces a transverse charge supercurrent in response to an equilibrium spin current. We verify the existence of the inverse superspin Hall effect both for a spin-polarized charge supercurrent and an exchange spin current, and propose that a φ 0 junction produced by the inverse superspin Hall effect can be used to directly and electrically measure the spin polarization of a charge supercurrent. This provides a possible way to solve the long-standing problem of how to directly detect the spin-polarization of supercurrents carried by triplet Cooper pairs. arXiv:1902.05555v2 [cond-mat.supr-con]

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Quasiparticle-mediated spin Hall effect in a superconductor

Cited by 100 publications

References 29 publications

Oscillatory Nernst effect in Pt|ferrite|cuprate-superconductor trilayer films

Oscillatory Nernst effect in Pt|ferrite|cuprate-superconductor trilayer films

Spin Hall effect and spin swapping in diffusive superconductors

Direct and inverse superspin Hall effect in two-dimensional systems: Electrical detection of spin supercurrents

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