High-energy quasiparticle injection into mesoscopic superconductors

Alegria, L. D.; L., Bøttcher, C. G.; Saydjari, Andrew K.; Pierce, Andrew T.; Lee, Seung Hwan; Harvey, Shannon; Vool, Uri; Yacoby, Amir

doi:10.1038/s41565-020-00834-8

Cited by 62 publications

(89 citation statements)

References 25 publications

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“…Ritter et al 16 ascribe the critical current quenching observed in titanium nitride nanowires to the injection of energetic electrons from the gate electrodes to the superconductor, which trigger the formation of a large number of quasiparticles that drive the nanowire back to the normal state. Alegria et al 17 and Golokolenov et al 18 support similar arguments to account for the behavior observed in electron tunneling spectroscopy experiments in titanium nanowires and in a vanadium waveguide resonator, respectively. On the other hand, Mercaldo et al 19 propose a theoretical model based on electric-field induced spin-orbit polarization at the surface, capable of modulating the phase and amplitude of the superconducting order parameter.…”

Section: Introductionmentioning

confidence: 54%

Critical current modulation induced by an electric field in superconducting tungsten-carbon nanowires

Orús

Fomin

Córdoba

2021

Sci Rep

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The critical current of a superconducting nanostructure can be suppressed by applying an electric field in its vicinity. This phenomenon is investigated throughout the fabrication and electrical characterization of superconducting tungsten-carbon (W-C) nanostructures grown by Ga$$^+$$ + focused ion beam induced deposition (FIBID). In a 45 nm-wide, 2.7 $$\upmu $$ μ m-long W-C nanowire, an increasing side-gate voltage is found to progressively reduce the critical current of the device, down to a full suppression of the superconducting state below its critical temperature. This modulation is accounted for by the squeezing of the superconducting current by the electric field within a theoretical model based on the Ginzburg–Landau theory, in agreement with experimental data. Compared to electron beam lithography or sputtering, the single-step FIBID approach provides with enhanced patterning flexibility and yields nanodevices with figures of merit comparable to those retrieved in other superconducting materials, including Ti, Nb, and Al. Exhibiting a higher critical temperature than most of other superconductors, in which this phenomenon has been observed, as well as a reduced critical value of the gate voltage required to fully suppress superconductivity, W-C deposits are strong candidates for the fabrication of nanodevices based on the electric field-induced superconductivity modulation.

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Section: Introductionmentioning

confidence: 54%

Critical current modulation induced by an electric field in superconducting tungsten-carbon nanowires

Orús

Fomin

Córdoba

2021

Sci Rep

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“…In previous studies, the origin of GCS was attributed to two different mechanisms, either to the effect of the applied electric field 12 − 21 , 25 − 28 or to high-energy quasiparticle injection via tunneling. 22 − 24 We will compare our experimental findings with these explanations in the following.…”

Section: Results and Discussionmentioning

confidence: 85%

Gate-Controlled Supercurrent in Epitaxial Al/InAs Nanowires

et al. 2021

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Gate-controlled supercurrent (GCS) in superconducting nanobridges has recently attracted attention as a means to create superconducting switches. Despite the clear advantages for applications, the microscopic mechanism of this effect is still under debate. In this work, we realize GCS for the first time in a highly crystalline superconductor epitaxially grown on an InAs nanowire. We show that the supercurrent in the epitaxial Al layer can be switched to the normal state by applying ≃±23 V on a bottom gate insulated from the nanowire by a crystalline hBN layer. Our extensive study of the temperature and magnetic field dependencies suggests that the electric field is unlikely to be the origin of GCS in our device. Though hot electron injection alone cannot explain our experimental findings, a very recent non-equilibrium phonons based picture is compatible with most of our results.

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“…The former results are in opposition with previous experiments [2-4] on the subject. We attribute this different behavior to the reduction in thermal coupling between the Dayem bridge and substrate compared to systems located on a substrate, whereas in terms of the microscopic origin of the gate-driven effect, the reduction in the switching current appears to be connected to a considerable increase in quasi-particle excitations in the superconducting system [21,23]. Such enhancements seem to be more efficient in suspended devices, in which the relaxation of quasiparticles via electron-phonon interactions is greatly reduced compared to conventional systems.…”

Section: Suspended Titanium Gate-controlled Transistormentioning

confidence: 89%

“…Figure 3b shows bilateral suppression of the supercurrent down to total quenching for |V G | 10 V in a range of bath temperature from 2 to 3.2 K. Notably, the sharper suppression of I S observed for positive values of the gate voltage is in contrast with a possible cold field-emission origin of the quenching effect. Indeed, the device geometry could facilitate electron extraction from the gate that occurs at negative gate bias values [21,22]. This consideration is deeply discussed in Section 3.…”

Section: Vanadium Gate-controlled Transistormentioning

confidence: 99%

“…Although some theories have been proposed, including surface nucleation and pinning of Abrikosov vortices [8,[11][12][13], the electric fielddriven Rashba orbital polarization [14][15][16][17], and the gate-driven Schwinger excitation of quasiparticles from the BCS vacuum [18][19][20], they have not been experimentally verified yet. The injection of high-energy field-emitted cold-electrons into the weak-link was also hypothesized to be at the origin of the gating effect [21,22]. Nevertheless, even in the presence of the latter mechanism, several experimental results are not compatible with a mere power injection, resulting in overheating of the superconductor [2,3,23,24].…”

Section: Introductionmentioning

confidence: 99%

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Gate Control of Superconductivity in Mesoscopic All-Metallic Devices

Puglia

Simoni²,

Giazotto³

2021

Materials

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The possibility to tune, through the application of a control gate voltage, the superconducting properties of mesoscopic devices based on Bardeen–Cooper–Schrieffer metals was recently demonstrated. Despite the extensive experimental evidence obtained on different materials and geometries, a description of the microscopic mechanism at the basis of such an unconventional effect has not been provided yet. This work discusses the technological potential of gate control of superconductivity in metallic superconductors and revises the experimental results, which provide information regarding a possible thermal origin of the effect: first, we review experiments performed on high-critical-temperature elemental superconductors (niobium and vanadium) and show how devices based on these materials can be exploited to realize basic electronic tools, such as a half-wave rectifier. Second, we discuss the origin of the gating effect by showing gate-driven suppression of the supercurrent in a suspended titanium wire and by providing a comparison between thermal and electric switching current probability distributions. Furthermore, we discuss the cold field-emission of electrons from the gate employing finite element simulations and compare the results with experimental data. In our view, the presented data provide a strong indication regarding the unlikelihood of the thermal origin of the gating effect.

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High-energy quasiparticle injection into mesoscopic superconductors

Cited by 62 publications

References 25 publications

Critical current modulation induced by an electric field in superconducting tungsten-carbon nanowires

Critical current modulation induced by an electric field in superconducting tungsten-carbon nanowires

Gate-Controlled Supercurrent in Epitaxial Al/InAs Nanowires

Gate Control of Superconductivity in Mesoscopic All-Metallic Devices

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