Observation of pair currents in superconductor-semiconductor contacts

Kastalsky, A.; Kleinsasser, A. W.; Greene, L. H.; Bhat, R.; Milliken, F. P.; Harbison, J. P.

doi:10.1103/physrevlett.67.3026

Cited by 309 publications

(282 citation statements)

References 13 publications

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“…Therefore, this model is not applicable to the wide spectral features with complex shapes corresponding to the Andreev reflection at the induced gap interface observed in our experiments and in previous low-T c work 23,24,27,28 . Moreover, our experimental results are also different from the low-T c results 25,39 . Our measurements show a proximity-induced gap feature with a wide region, appearing immediately below T c with almost twice the normal conductance (Figs 3c and 4b).…”

Section: Discussioncontrasting

confidence: 99%

“…The proximity-induced superconductivity was established in low-T c junctions with a metal 23,24 , or a semiconductor 25,26 as the N-contact. Specifically, Andreev reflection features with the width corresponding to the induced gap in the normal material, along with a reduced gap in the superconductor, were shown to manifest the signature of the proximity effect 23,24,27,28 .…”

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confidence: 99%

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Proximity-induced high-temperature superconductivity in the topological insulators Bi2Se3 and Bi2Te3

et al. 2012

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Interest in the superconducting proximity effect has been reinvigorated recently by novel optoelectronic applications as well as by the possible emergence of the elusive majorana fermion at the interface between topological insulators and superconductors. Here we produce high-temperature superconductivity in Bi 2 se 3 and Bi 2 Te 3 via proximity to Bi 2 sr 2 CaCu 2 o 8 + δ , to access higher temperature and energy scales for this phenomenon. This was achieved by a new mechanical bonding technique that we developed, enabling the fabrication of highquality junctions between materials, unobtainable by conventional approaches. We observe proximity-induced superconductivity in Bi 2 se 3 and Bi 2 Te 3 persisting up to at least 80 K-a temperature an order of magnitude higher than any previous observations. moreover, the induced superconducting gap in our devices reaches values of 10 mV, significantly enhancing the relevant energy scales. our results open new directions for fundamental studies in condensed matter physics and enable a wide range of applications in spintronics and quantum computing.

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Section: Discussioncontrasting

confidence: 99%

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confidence: 99%

Proximity-induced high-temperature superconductivity in the topological insulators Bi2Se3 and Bi2Te3

et al. 2012

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“…However, it is well known that the proximity effect in N/S structures induces a condensate in the normal metal which causes a subgap conductance in N/S junctions. 52,53 In order to quantify the proximity effect, we need boundary conditions that take into account the spin filtering at the N/S barrier. Surprisingly, in spite of many works on N/S and F /S structures such boundary conditions are absent in the literature.…”

Section: Subgap Conductance In N/i Sf /S Junctions: Effective Boumentioning

confidence: 99%

Electronic transport through ferromagnetic and superconducting junctions with spin-filter tunneling barriers

2012

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We present a theoretical study of the quasiparticle and subgap conductance of generic X/I sf /S M junctions with a spin-filter barrier I sf , where X is either a normal N or a ferromagnetic metal F and S M is a superconductor with a built-in exchange field. Our study is based on the tunneling Hamiltonian and the Green's-function technique. First, we focus on the quasiparticle transport, both above and below the superconducting critical temperature. We obtain a general expression for the tunneling conductance which is valid for arbitrary values of the exchange field and arbitrary magnetization directions in the electrodes and in the spin-filter barrier. In the second part, we consider the subgap conductance of a N/I sf /S junction, where S is a conventional superconductor. In order to account for the spin-filter effect at interfaces, we heuristically derive boundary conditions for the quasiclassical Green's functions. With the help of these boundary conditions, we show that the proximity effect and the subgap conductance are suppressed by spin filtering in a N/I sf /S junction. Our work provides useful tools for the study of spin-polarized transport in hybrid structures both in the normal and in the superconducting state.

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“…Since the pioneering work of Kastalsky et al, 19 most studies of AR in semiconductors have been carried out in a two-dimensional ͑2D͒ geometry. This is not surprising, as serious problems are anticipated for AR experiments in a superconductor-semiconductor ͑S/Sm͒ junction in a threedimensional ͑3D͒ geometry because of the high resistivity of semiconductors at low temperatures and the presence of a Schottky barrier in most S / Sm contacts.…”

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confidence: 99%

Andreev reflection and pair-breaking effects at the superconductor/magnetic semiconductor interface

Panguluri

Wójtowicz

et al. 2005

Phys. Rev. B

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We investigate the applicability of spin polarization measurements using Andreev reflection in a point contact geometry in heavily doped dilute magnetic semiconductors, such as (Ga,Mn)As. While we observe conventional Andreev reflection in non-magnetic (Ga,Be)As epilayers, our measurements indicate that in ferromagnetic (Ga,Mn)As epilayers with comparable hole concentration the conductance spectra can only be adequately described by a broadened density of states and a reduced superconducting gap. We suggest that these pair-breaking effects stem from inelastic scattering in the metallic impurity band of (Ga,Mn)As and can be explained by introducing a finite quasiparticle lifetime or a higher effective temperature. For (Ga,Mn)As with 8% Mn concentration and 140 K Curie temperature we evaluate the spin polarization to be 83 ± 17%.

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Observation of pair currents in superconductor-semiconductor contacts

Cited by 309 publications

References 13 publications

Proximity-induced high-temperature superconductivity in the topological insulators Bi2Se3 and Bi2Te3

Proximity-induced high-temperature superconductivity in the topological insulators Bi2Se3 and Bi2Te3

Electronic transport through ferromagnetic and superconducting junctions with spin-filter tunneling barriers

Andreev reflection and pair-breaking effects at the superconductor/magnetic semiconductor interface

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