Sub-micrometer-sized, cross-type Nb–AlOx–Nb tunnel junctions with low parasitic capacitance

Anders, S.; Schmelz, M.; Fritzsch, L.; Stolz, R.; Zakosarenko, V.; Schönau, Thomas; Meyer, H.‐G.

doi:10.1088/0953-2048/22/6/064012

Cited by 49 publications

(43 citation statements)

References 30 publications

(33 reference statements)

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“…The SIS junction based SQUIDs offer a higher voltage swing resulting in a better performance than comparable to SNS or SNIS junctions. They employed a technology based on sub-micron cross-type Nb/AlOx/Nb fabrication [198]. The nanoSQUID depicted in the Fig.…”

Section: Nanosquid Based On Sandwich Type Nanojunctionsmentioning

confidence: 99%

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: Nanosquid Based On Sandwich Type Nanojunctionsmentioning

confidence: 99%

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

2016

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“…For the susceptometer with the lowest SQUID inductance, L  12 pH, a flux noise level of 0.2 µ 0 /Hz is predicted at 4.2 K comparable with today's best nanoSQUIDs. By patterning a nanoloop of 100 nm minimum line width and spacing into the pickup loop, transfer coefficients of up to 25 n 0 /µ B can be obtained, which allows for a very low equivalent spin noise down to 8 µ B /Hz at 4.2 K. The noise level could be further improved by using smaller Josephson junctions, which also reduces the effect of the excitation field on the junctions [3], [17]. Another option is cooling the devices to mK temperatures.…”

Section: Discussionmentioning

confidence: 99%

Thin-Film Microsusceptometer With Integrated Nanoloop

Drung

Storm

Ruede

et al. 2014

IEEE Trans. Appl. Supercond.

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We report the design and performance of thin-film microsusceptometers intended for magnetic measurements on samples at variable temperature down to the low mK range and excitation frequencies of up to about 1 MHz. The devices are realized as first-order gradiometers with two circular loops of 60 µm or 30 µm average diameter resulting in a total inductance of 360 pH or 250 pH, respectively. An integrated excitation coil generates a magnetic field with a transfer coefficient of 0.1 T/A at the sample position, whereas the Josephson junctions are located in a field-reduced area. The susceptometers are fabricated by a conventional Nb/AlOx/Nb trilayer process. In order to enhance the sensitivity to the level required for the measurement of subµm samples, an extra detection loop of 450 nm inner diameter was integrated into one of the pickup loops by using a focused ion beam (FIB). We show that this device is able of detecting signals from very small permalloy samples. An optimized susceptometer design with a predicted SQUID inductance of 12 pH is also presented, that can achieve an equivalent spin noise of 8 µ B /Hz at 4.2 K (µ B is the Bohr magneton) when being equipped with a nanoloop of 100 nm line width and separation. Keywords-Focused ion beam (FIB); microsusceptometer; nanoloop; permalloy; superconducting quantum interference device (SQUID)I.

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“…The cross-type fabrication process has been described in detail, together with the characterization of the junctions, in Ref. 24. Figure 4 shows an example of a cross-type Josephson junction.…”

Section: Cross-type Technologymentioning

confidence: 99%

Application and fabrication aspects of sub-micrometer-sized Josephson junctions

Oelsner

Hübner

Anders

et al. 2017

Low Temperature Physics

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We present two possible methods for the fabrication of sub-micron sized Josephson junctions, namely the shadow-evaporation technique and the cross-type technology. Their importance for the field of modern superconducting technology is discussed. As examples we present measurement results of a two-qubit sample and a prototype of a microwave detector fabricated each by one of the described methods. We review potential applications of superconducting quantum circuits based on the developed methods.

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Sub-micrometer-sized, cross-type Nb–AlOx–Nb tunnel junctions with low parasitic capacitance

Cited by 49 publications

References 30 publications

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

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

Thin-Film Microsusceptometer With Integrated Nanoloop

Application and fabrication aspects of sub-micrometer-sized Josephson junctions

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