Noise theory of dc nano-SQUIDs based on Dayem nanobridges

Granata, C.; Vettoliere, A.; Russo, M.; Ruggiero, B.

doi:10.1103/physrevb.84.224516

Cited by 29 publications

(20 citation statements)

References 34 publications

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“…For L/ξ greater than 3.5, the curve becomes double valued. b) Maximum critical current as a function of the L/ξ ratio (adapted from [126]). ratio, by varying the a 0 parameter in (32), the corresponding j 0 values is found by using a scalar nonlinear zero finding function.…”

Section: Theoretical Aspects Of Dayem Bridgesmentioning

confidence: 99%

“…Fig.16 a) Voltage vs. magnetic flux characteristics corresponding to three different L/ξ values, computed for two different values of bias current. b) Flux-to-voltage transfer factor V Φ as a function of the bias current for different L/ξ ratios obtained by evaluating the derivative of the V-Φ characteristics at Φ e = Φ 0 /4 (adapted from [126]).…”

Section: Nanosquid Performance Predictionsmentioning

confidence: 99%

“…An empirical expression of the white flux noise was derived from the above simulations [126]: (36) where A(Γ) and B(Γ) are numerical coefficient which depend on Γ value. It was obtained by fitting the behaviour of the flux noise as a function of L/ξ value.…”

Section: As Shown Inmentioning

confidence: 99%

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Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

2016

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The magnetic sensing at nanoscale level is a promising and interesting research topic of nanoscience. Indeed, magnetic imaging is a powerful tool for probing biological, chemical and physical systems. The study of small spin cluster, like magnetic molecules and nanoparticles, single electron, cold atom clouds, is one of the most stimulating challenges of applied and basic research of the next years. In particular, the magnetic nanoparticle investigation plays a fundamental role for the modern material science and its relative technological applications like ferrofluids, magnetic refrigeration and biomedical applications, including drug delivery, hyper-thermia cancer treatment and magnetic resonance imaging contrast-agent. Actually, one of the most ambitious goals of the high sensitivity magnetometry is the detection of elementary magnetic moment or spin. In this framework, several efforts have been devoted to the development of a high sensitivity magnetic nanosensor pushing sensing capability to the individual spin level. Among the different magnetic sensors, Superconducting QUantum Interference Devices (SQUIDs) exhibit an ultra high sensitivity and are widely employed in numerous applications. Basically, a SQUID consists of a superconducting ring (sensitive area) interrupted by two Josephson junctions. In the recent years, it has been proved that the magnetic response of nano-objects can be effectively measured by using a SQUID with a very small sensitive area (nanoSQUID). In fact, the sensor noise, expressed in terms of the elementary magnetic moment (spin or Bohr magneton), is linearly dependent on the SQUID loop side length. For this reason, SQUIDs have been progressively miniaturized in order to improve the sensitivity up to few spin per unit of bandwidth. With respect to other techniques, nanoSQUIDs offer the advantage of direct measurement of magnetization changes in small spin systems. In this

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Section: Theoretical Aspects Of Dayem Bridgesmentioning

confidence: 99%

Section: Nanosquid Performance Predictionsmentioning

confidence: 99%

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Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

2016

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“…electrical properties, demanding precise control of the film thickness and quality on the sub-nanometer level. Moreover, the progress in the field of integrated SQUID technology has substantially driven the development of nanostructured ultrathin niobium films, currently reaching lateral feature sizes of tens of nanometers 24 25 26 27 . In contrast to gold, niobium films reveal substantially better adhesion to glass, in particular to silica, leading to solid metallic films which cannot be mechanically removed from glass surfaces without destroying the actual sample surface.…”

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confidence: 99%

Ultrathin niobium nanofilms on fiber optical tapers – a new route towards low-loss hybrid plasmonic modes

Wieduwilt

Tuniz

Linzen

et al. 2015

Sci Rep

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Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have recently gained substantial attention in plasmonics, e.g. as building blocks of metasurfaces. Typically, noble metals such as silver or gold are the materials of choice, due to their excellent optical properties, however they also possess some intrinsic disadvantages. Here, we introduce niobium nanofilms (~10 nm thickness) as an alternate plasmonic platform. We demonstrate functionality by depositing a niobium nanofilm on a plasmonic fiber taper, and observe a dielectric-loaded niobium surface-plasmon excitation for the first time, with a modal attenuation of only 3–4 dB/mm in aqueous environment and a refractive index sensitivity up to 15 μm/RIU if the analyte index exceeds 1.42. We show that the niobium nanofilm possesses bulk optical properties, is continuous, homogenous, and inert against any environmental influence, thus possessing several superior properties compared to noble metal nanofilms. These results demonstrate that ultrathin niobium nanofilms can serve as a new platform for biomedical diagnostics, superconducting photonics, ultrathin metasurfaces or new types of optoelectronic devices.

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“…If a grain boundary existed within one microbridge but not the other it is very improbable that theoretical critical currents would be so well matched. The high value of Δi c also implies that the microbridges are smaller in width and length on the scale of the superconducting cohenernce length [14], [15] It is also interesting to estimate the energy sensitivity ε n of these nanoSQUIDs, defined by…”

Section: Discussionmentioning

confidence: 99%

Investigating the Intrinsic Noise Limit of Dayem Bridge NanoSQUIDs

Patel

Gallop

et al. 2014

IEEE Trans. Appl. Supercond.

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NanoSQUIDs made from Nb thin films have been produced with nanometre loop sizes down to 200 nm, using weak-link junctions with dimensions less than 60 nm. These composite (W/Nb) single layer thin film devices, patterned by FIB milling, show extremely good low-noise performance ∼170 nΦ 0 at temperatures between 5 and 8.5 K and can operate in rather high magnetic fields (at least up to 1 T). The devices produced so far have a limited operating temperature range, typically only 1-2 K. We have the goal of achieving operation at 4.2 K, to be compatible with the best SQUID series array (SSA) preamplifier available. Using the SSA to readout the nanoSQUIDs provides us with a means of investigating the intrinsic noise of the former. In this paper we report improved white noise levels of these nanoSQUIDs, enabling potential detection of a single electronic spin flip in a 1-Hz bandwidth. At low frequencies the noise performance is already limited by SSA preamplifier noise.Index Terms-NanoSQUIDs, noise measurements, T c suppression. 1051-8223

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Noise theory of dc nano-SQUIDs based on Dayem nanobridges

Cited by 29 publications

References 34 publications

Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

Nano Superconducting Quantum Interference device: A powerful tool for nanoscale investigations

Ultrathin niobium nanofilms on fiber optical tapers – a new route towards low-loss hybrid plasmonic modes

Investigating the Intrinsic Noise Limit of Dayem Bridge NanoSQUIDs

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