Nanobridge superconducting quantum interference devices: Beyond the Josephson limit

Hazra, Dibyendu

doi:10.1103/physrevb.99.144505

Cited by 10 publications

(7 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, improvement of spatial resolution is still a challenging task. The apparent solution of this limitation seems to be a decrease in the geometrical dimensions of the SQUID [8][9][10][11][12]. It is the essential reason why SQUIDs of nanoscale dimensions attract the interest and efforts of numerous groups worldwide.…”

Section: Introductionmentioning

confidence: 99%

Planar MoRe-based direct current nanoSQUID

Shishkin

Skryabina

Гуртовой

et al. 2020

Supercond. Sci. Technol.

View full text Add to dashboard Cite

We have developed planar nanoSQUID with nanobridge-type Josephson junctions based on the oxidation resistant and high H c2 MoRe alloy. The objective of the research was to reduce size of the SQUID loop with the aim being to reduce magnetic flux noise and improve the spatial resolution of the SQUID sensors. Employing RF-magnetron sputtering, electron-beam lithography, and reactive ion etching in CHF 3 + O 2 plasma using Al hard masks, we have realized nanoSQUIDs with Josephson junctions in the form of 30 − 50 nm wide nanobridges and an effective magnetic flux capture radius of ~95 nm. The critical temperature of the fabricated devices was T c = 7.9 K. The I(V)-characteristics demonstrated critical current I 0 ≃ 114 µA at 4.2 K and modulation period in magnetic fields of ~700 Oe.

show abstract

Section: Introductionmentioning

confidence: 99%

Planar MoRe-based direct current nanoSQUID

Shishkin

Skryabina

Гуртовой

et al. 2020

Supercond. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…In this work, we report the development of a batch fabrication process for SOC by taking advantage of the robustness of 3D nano-bridge junctions 23,24,25 so that deep silicon etching 26,27 could be utilized. This step generated a sharp edge around the pick-up loop which enabled scanning in close proximity to the sample surface.…”

mentioning

confidence: 99%

Improving spatial resolution of scanning SQUID microscopy with an on-chip design

Pan¹,

Zhu²,

Feng³

et al. 2021

Supercond. Sci. Technol.

View full text Add to dashboard Cite

Scanning superconducting quantum interference device microscopy (sSQUID) is currently one of the most effective methods for direct and sensitive magnetic flux imaging on the mesoscopic scale. A SQUID-on-chip design allows integration of field coils for susceptometry in a gradiometer setup which is very desirable for measuring magnetic responses of quantum matter. However, the spatial resolution of such a design has largely been limited to micrometers due to the difficulty in approaching the sample. Here, we used electron beam lithography technology in the fabrication of the 3D nano-bridge-based SQUID devices to prepare pick-up coils with diameters down to 150 nm. Furthermore, we integrated the deep silicon etching process in order to minimize the distance between the pick-up coil and the wafer edge. Combined with a tuning-fork-based scanning head, the sharpness of the etched chip edge enables a precision of 5 nm in height control. By scanning measurements on niobium chessboard samples using these improved SQUID devices, we demonstrate sub-micron spatial resolutions in both magnetometry and susceptometry, significantly better than our previous generations of nano-SQUIDs. Such improvement in spatial resolution of SQUID-on-chip is a valuable progress for magnetic imaging of quantum materials and devices in various modes.Scanning superconducting quantum interference device microscopy (sSQUID) has become an important magnetic imaging technique to study superconductivity, magnetism and band topology in quantum materials and devices in reduced dimensions 1,2,3 . The direct flux sensitivity of sSQUID is a fundamental advantage over techniques relying on short-range magnetic interactions for magnetic sensitivity (e.g., MFM 4 , spin-polarized STM 5 , magnetic exchange-force microscopy 6 , spin-polarized low energy electron microscopy 7 , scanning NV microscopy 8 ). It liberates sSQUID from stringent requirements on the cleanness of sample surface and greatly facilitates its application to a broad range of material systems, interfaces of heterostructures 9 and even device prototypes made of new materials 10,11 .

show abstract

“…From equation 2 and the second Josephson relation [38,39], it is clear that the j-th weak link behaves as an inductor with kinetic inductance L Kj = Φ0 2π ϕcj Icj , where Φ 0 is the magnetic flux quantum (see equation 1 and the electrical model in figure 1). For the typical lengths of the Dayem bridges explored in this work (approximately 150 nm), a linear CΦR represents a reasonable approximation in the explored low temperature range T T c [22]. Indeed, by solving the Ginzburg-Landau equations, it has been shown that for nanobridges longer than 3ξ(T ), the CΦR becomes multivalued and progressively more linear [19,40].…”

Section: Properties Of a Squid Containing Two Nominally Different Day...mentioning

confidence: 62%

“…Using this method, we conduct an experimental study of lithographically fabricated MoGe superconducting nanobridges and their current phase relation (CΦR). The latter is approximately given by [18][19][20][21][22]…”

Section: Introductionmentioning

confidence: 99%

The impact of kinetic inductance on the critical current oscillations of nanobridge SQUIDs

Dausy,

Nulens,

Raes

et al. 2021

Preprint

View full text Add to dashboard Cite

In this work, we study the current phase relation (CΦR) of lithographically fabricated molybdenum germanium (MoGe) nanobridges, which is intimately linked to the nanobridge kinetic inductance. We do this by imbedding the nanobridges in a SQUID. We observe that for temperatures far below Tc, the CΦR is linear as long as the condensate is not weakened by the presence of supercurrent. We demonstrate lithographic control over the nanobridge kinetic inductance, which scales with the nanobridge aspect ratio. This allows to tune the SQUID Ic(B) characteristic. The SQUID properties that can be controlled in this way include the SQUID sensitivity and the positions of the critical current maxima. These observations can be of use for the design and operation of future superconducting devices such as magnetic memories or flux qubits.

show abstract

Nanobridge superconducting quantum interference devices: Beyond the Josephson limit

Cited by 10 publications

References 66 publications

Planar MoRe-based direct current nanoSQUID

Planar MoRe-based direct current nanoSQUID

Improving spatial resolution of scanning SQUID microscopy with an on-chip design

The impact of kinetic inductance on the critical current oscillations of nanobridge SQUIDs

Contact Info

Product

Resources

About