Percolation model of excess electrical noise in transition-edge sensors

Lindeman, M. A.; Anderson, M. B.; Bandler, S. R.; Bilgri, N.; Chervenak, James A.; Crowder, S. G.; Fallows, S.; Figueroa‐Feliciano, E.; Finkbeiner, F. M.; Iyomoto, Naoko; Kelley, R. L.; Kilbourne, C. A.; Lai, Tenghsien; Man, Jiaxiu; McCammon, D.; Nelms, K. L.; Porter, F. S.; Rocks, L.; Saab, T.; Sadleir, J. E.; Vidugiris, G.

doi:10.1016/j.nima.2005.12.114

Cited by 10 publications

(19 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A reduction in both α and β caused by the bars is evident and we also see a ratio α/β ≈ 10, agreeing with experimental observations. 10,13,21 18,37 , α and hence β are reduced as N increases. Comparison of curves (c) and (d) shows the reduction of α and hence β by an applied field.…”

Section: Resultsmentioning

confidence: 97%

Modelling proximity effects in transition edge sensors to investigate the influence of lateral metal structures

Harwin¹,

Goldie²,

Withington³

2017

Supercond. Sci. Technol.

View full text Add to dashboard Cite

The bilayers of Transition Edge Sensors (TESs) are often modified with additional normal-metal features such as bars or dots. Previous device measurements suggest that these features improve performance, reducing electrical noise and altering response times. However, there is currently no numerical model to predict and quantify these effects. Here we extend existing techniques based on Usadel's equations to describe TESs with normal-metal features. We show their influence on the principal TES characteristics, such as the small-signal electrothermal parameters α and β and the superconducting transition temperature Tc. Additionally, we examine the effects of an applied magnetic field on the device performance. Our model predicts a decrease in Tc, α and β as the number of lateral metal structures is increased. We also obtain a relationship between the length L of a TES and its critical temperature, Tc ∝ L −0.7 for a bilayer with normal-metal bars. We predict a periodic magnetic flux dependence of α, β and Ic. Our results demonstrate good agreement with published experimental data, which also show the reduction of α, β and Tc with increasing number of bars. The observed Fraunhofer dependence of critical current on magnetic flux is also anticipated by our model. The success of this model in predicting the effects of additional structures suggests that in the future numerical methods can be used to better inform the design of TESs, prior to device processing.

show abstract

Section: Resultsmentioning

confidence: 97%

Modelling proximity effects in transition edge sensors to investigate the influence of lateral metal structures

Harwin¹,

Goldie²,

Withington³

2017

Supercond. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…Percolation models have garnered attention in recent years in efforts to explain the resistive transition in TESs. 14,15 It was hypothesized that added N fingers changed the TES transition behavior by altering the geometry of the percolating paths between electrodes. In this section we apply a percolation analysis to our TES devices and compare with measurements of the resistive transition.…”

Section: Tc and ∆Tc Change With Au Fingers Inconsistent With Percolat...mentioning

confidence: 99%

“…The richness of physics arising from S-N heterostructures is considerable and with potential applications including improved magnetic sensing, nanocoolers, particle detection, THz electronics, and superconducing qubits. [9][10][11] Previous attempts to model the TES resistive transition include using Kosterlitz-Thouless-Berezinski (KTB) theory, 12 fluctuation superconductivity, 13 percolation theory for a random superconducting resistor network, 14,15 and thermal fluctuation models. 16 We have recently shown both experimentally and theoretically that TESs exhibit weak-link behavior, where, unlike previous models, the average order parameter varies over the TES.…”

Section: Introductionmentioning

confidence: 99%

Proximity effects and nonequilibrium superconductivity in transition-edge sensors

et al. 2011

View full text Add to dashboard Cite

We have recently shown that normal-metal/superconductor (N/S) bilayer TESs (superconducting Transition-Edge Sensors) exhibit weak-link behavior. 1 Here we extend our understanding to include TESs with added noise-mitigating normal-metal structures (N structures). We find TESs with added Au structures also exhibit weak-link behavior as evidenced by exponential temperature dependence of the critical current and Josephson-like oscillations of the critical current with applied magnetic field. We explain our results in terms of an effect converse to the longitudinal proximity effect (LoPE) 1 , the lateral inverse proximity effect (LaiPE), for which the order parameter in the N/S bilayer is reduced due to the neighboring N structures. Resistance and critical current measurements are presented as a function of temperature and magnetic field taken on square Mo/Au bilayer TESs with lengths ranging from 8 to 130 µm with and without added N structures. We observe the inverse proximity effect on the bilayer over in-plane distances many tens of microns and find the transition shifts to lower temperatures scale approximately as the inverse square of the inplane N-structure separation distance, without appreciable broadening of the transition width. We also present evidence for nonequilbrium superconductivity and estimate a quasiparticle lifetime of 1.8 × 10 −10 s for the bilayer. The LoPE model is also used to explain the increased conductivity at temperatures above the bilayer's steep resistive transition.

show abstract

“…While there exist a few suitable elemental superconductors, the best results have been achieved using proximitycoupled, superconductor/normal-metal (S/N) bilayers 2,3 , for which T c is tuned by selection of the thicknesses of the S and N layers. 4 There have been a variety of models 4,5,6,7,8 used to explain the noise, T c , and ∆T c in TES bilayers, all assuming spatially uniform devices. Though some have been shown to be consistent with certain aspects of particular devices, they do not explain measured T c and ∆T c in S/N bilayer TESs generally.…”

mentioning

confidence: 99%

“…(7) The integrals in Eqs. (5), (6), and (7) can be evaluated numerically as in Ref. 20 or in terms of elliptic integrals as in Refs.…”

mentioning

confidence: 99%

Longitudinal Proximity Effects in Superconducting Transition-Edge Sensors

et al. 2010

View full text Add to dashboard Cite

We have found experimentally that the critical current of a square superconducting transition-edge sensor (TES) depends exponentially upon the side length L and the square root of the temperature T . As a consequence, the effective transition temperature Tc of the TES is current-dependent and at fixed current scales as 1/L 2 . We also have found that the critical current can show clear Fraunhoferlike oscillations in an applied magnetic field, similar to those found in Josephson junctions. The observed behavior has a natural theoretical explanation in terms of longitudinal proximity effects if the TES is regarded as a weak link between superconducting leads. We have observed the proximity effect in these devices over extraordinarily long lengths exceeding 100 µm.PACS numbers: 74.78.Bz,74.25.Op A superconductor cooled through its transition temperature T c while carrying a finite dc bias current undergoes an abrupt decrease in electrical resistance from its normal-state value R N to zero.Superconducting transition-edge sensors (TESs) exploit this sharp transition; these devices are highly sensitive resistive thermometers used for precise thermal energy measurements. 1 TES microcalorimeters have been developed with measured energy resolutions in the X-ray and gamma-ray band of ∆E = 1.8±0.2 eV FWHM at 6 keV, 2 and ∆E = 22 eV FWHM at 97 keV, 3 respectively-with the latter result at present the largest reported E/∆E of any non-dispersive photon spectrometer. TESs are successfully used across much of the electromagnetic spectrum, measuring the energy of single-photon absorption events from infrared to gamma-ray energies and photon fluxes out to the microwave range. 1 Despite these experimental successes, the dominant physics governing TESs biased in the superconducting phase transition remains poorly understood. 1 To achieve high energy resolution it is important to control both the TES's T c and its transition width ∆T c . Because the energy resolution of calorimeters improves with decreasing temperature, they are typically designed to operate at temperatures around 0.1 K. For a TES, this requires a superconductor with T c in that range. While there exist a few suitable elemental superconductors, the best results have been achieved using proximitycoupled, superconductor/normal-metal (S/N) bilayers 2,3 , for which T c is tuned by selection of the thicknesses of the S and N layers. 4 There have been a variety of models 4-8 used to explain the noise, T c , and ∆T c in TES bilayers, all assuming spatially uniform devices. Though some have been shown to be consistent with certain aspects of particular devices, they do not explain measured T c and ∆T c in S/N bilayer TESs generally.In this paper we emphasize the importance of a phenomenon that so far has been neglected in previous theoretical studies of TESs: the longitudinal proximity effect.Since the square bilayers at the heart of the TES are connected at opposite ends to superconducting leads with transition temperatures well above the intrinsic transition temperatur...

show abstract

Percolation model of excess electrical noise in transition-edge sensors

Cited by 10 publications

References 2 publications

Modelling proximity effects in transition edge sensors to investigate the influence of lateral metal structures

Modelling proximity effects in transition edge sensors to investigate the influence of lateral metal structures

Proximity effects and nonequilibrium superconductivity in transition-edge sensors

Longitudinal Proximity Effects in Superconducting Transition-Edge Sensors

Contact Info

Product

Resources

About