Suppression of the superconducting energy gap in intrinsic Josephson junctions of Bi2Sr2CaCu2O8+ single crystals

You, Lixing; Wu, Peiheng; Chen, J; Xu, Wei; Kajiki, K; Watauchi, Satoshi; Tanaka, Isao

doi:10.1088/0953-2048/17/10/013

Cited by 10 publications

(11 citation statements)

References 37 publications

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“…This recombination radiation, R 2, results in partial depairing and increase of QP population in mesa D, which is sensed by the detector C. Since only the generator D is in direct contact with the detector C, the response from D is stronger (discontinuity in the IVC) than from B (peak in the derivative). The response can be attributed to appearance of in-plane resistance between mesas B and C [23], and to imbalance in QP population between mesas D and C [24], leading to appearance of negative voltage at mesa C similar in origin to the built-in potential in n-p junctions. Both types of responses enhance with increasing depairing in mesa D.…”

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confidence: 99%

Quantum Cascade Phenomenon inBi2Sr2CaCu2O8+δSingle Crystals

Krasnov

2006

Phys. Rev. Lett.

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We study interlayer transport in Bi2Sr2CaCu2O(8+delta) cuprates, which represent stacks of atomic scale intrinsic Josephson junctions. A series of resonant dips in conductance is observed at condition when bremsstrahlung and recombination bands in nonequilibrium spectrum of Josephson junctions overlap. The phenomenon is explained in terms of self-detection of a new type of collective strongly nonequilibrium state in natural atomic superlattices, bearing certain resemblance with operation of a quantum cascade laser. Conclusions are supported by in situ generation-detection experiments and by numerical simulations.

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confidence: 99%

Quantum Cascade Phenomenon inBi2Sr2CaCu2O8+δSingle Crystals

Krasnov

2006

Phys. Rev. Lett.

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“…An effective SIJJ could be seen in the 4-probe measurements on such a mesa. However, extra junctions under the electrodes can give rise to unwanted local heating [7,8].In this letter, we report on reproducible fabrication of uniform stacks formed inside the very thin (d ∼ 100 nm) pieces of BSCCO single crystals by using a double-sided etching technique [9]. The number of junctions in the stacks can be tailor-made to any small number N < 10 including the important case of N = 1 (a single-junction stack).…”

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confidence: 99%

“…An effective SIJJ could be seen in the 4-probe measurements on such a mesa. However, extra junctions under the electrodes can give rise to unwanted local heating [7,8].…”

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confidence: 99%

Single intrinsic Josephson junction with double-sided fabrication technique

You

Torstensson

Yurgens

et al. 2006

Applied Physics Letters

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We make stacks of intrinsic Josephson junctions (IJJs) imbedded in the bulk of very thin (d ≤ 100 nm) Bi2Sr2CaCu2O8+x single crystals. By precisely controlling the etching depth during the double-sided fabrication process, the stacks can be reproducibly tailor-made to be of any microscopic height (0 − 9 nm < d), i.e. enclosing a specified number of IJJ (0 − 6), including the important case of a single junction. We discuss reproducible gap-like features in the current-voltage characteristics of the samples at high bias. [1,2]. A BSCCO single crystal in the c-axis direction can thus be viewed as a large array of very thin (1.5 nm) intrinsic Josephson junctions (IJJs) in series. At present, this is perhaps the only reliable way to obtain HTS SIS junctions. These junctions appear to have high potential for high-frequency applications like heterodyne receivers and quantum voltage standards [3,4].It is difficult to isolate and study individual IJJ. Most of applications and research on IJJs use therefore stacks containing many junctions. The stacks can be formed either on the surfaces of single crystals (mesas) or etched out in the middle of BSCCO whiskers using focussed ion beams [5]. Earlier we developed a method for making a single intrinsic Josephson junction (SIJJ) enclosed in a U-shaped mesa structure [6]. An effective SIJJ could be seen in the 4-probe measurements on such a mesa. However, extra junctions under the electrodes can give rise to unwanted local heating [7,8].In this letter, we report on reproducible fabrication of uniform stacks formed inside the very thin (d ∼ 100 nm) pieces of BSCCO single crystals by using a double-sided etching technique [9]. The number of junctions in the stacks can be tailor-made to any small number N < 10 including the important case of N = 1 (a single-junction stack). As the stacks are imbedded in the superconducting material, i.e. there are no direct resistive contacts to them, heating effects can be minimized in such stacks allowing the genuine current-voltage (I-V) characteristics to be traced out. Devices like SQUIDs are feasible to make using the developed technique.The stack-fabrication routines start with evaporation of an Au thin film on a freshly cleaved crystal glued onto a sapphire substrate using polyimide. Using the conventional photolithography and Ar-ion etching, a bow-tieshaped mesa with a micro-bridge in the center is formed on the crystal. The overall thickness of this mesa d is typically about 100 nm which is controlled by etching time and rate. Then, a 40 nm d/2 deep slit is made across the bridge. In the next step, we flip the sample and glue it onto another sapphire substrate, sandwiching the single crystal between the two substrates. Separating the substrates cleaves the single crystal into two pieces, one with the mesa being flipped upside down and glued to the second substrate. We subsequently remove all material but the mesa by iteratively cleaving the former with the aid of Scotch tape and inspecting the resulting sample in optical microscope. A ne...

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“…The junction's critical current is 4.4 mA, the critical current density is 733 A/cm 2 and the gap voltage is 14 mV (this small voltage is due to the heating effect [7,9] ). Meanwhile, there is a surface junction [10,11] in it, which has a small gap parameter and critical current (4 mV and 3.8 mA).…”

Section: Methodsmentioning

confidence: 99%

“…Due to high anisotropic and small specific heat in BSCCO, especially the covered insulated layer, the heat effect becomes more serious, thus affects our results. We can observe the back bendsing [7,9] from the I-V curve in Figure 7. We think that the back bending results from the joule heat.…”

Section: Methodsmentioning

confidence: 99%

Acid etching process for fabrication of Bi2Sr2CaCu2O8+x stack

Zhang

Chen

et al. 2007

CHINESE SCI BULL

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We adopted a new method, acid etching process, to fabricate the intrinsic Josephson junctions based on the Bi 2 Sr 2 CaCu 2 O 8+x single crystals. By soaking the crystals into the dilute hydrochloric acid, we fabricated a junction stack successfully, and meantime made the surrounding area insulated. A certain concentration of hydrochloric acid was used to maintain the roughness of the modified layer. The current-voltage characteristic was achieved through the four terminal measurement. We could control the junctions' number by changing the concentration and the soaking time. We also found that the thickness of the stack was equal to the average height of the insulation layer. Such a simple, convenient and controllable fabrication method with a high yield might widen the applications of the intrinsic Josephson junctions. acid etching process, intrinsic Josephson junction, concentration, four-terminal measurementSince the pioneering work of Kleiner et al. [1] , the intrinsic Josephson junctions (IJJs) have become a hot topic in high temperature superconductivity (HTS), and the technology for fabrication of IJJs has been founded and developed. Conventional method to fabricate a Bi 2 Sr 2 -CaCu 2 O 8+x (BSCCO) stack is argon ion milling. There are several outstanding advantagements, such as fabrication of single IJJ [2] (SIJJ), double-side fabrication method [3] and controllable Bi 2 Sr 2 CaCu 2 O 8+x /Au contacts fabrication [4] . As ion beam etching (IBE) technology is common and successful, it can be used to fabricate IJJs for different purposes. All the aforementioned methods have their own features, but the complicated process with a low output of good samples may restrict the application of IJJs. In this work, we adopted a new process to fabricate the BSCCO stack--acid etching process.

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Suppression of the superconducting energy gap in intrinsic Josephson junctions of Bi₂Sr₂CaCu₂O₈₊single crystals

Cited by 10 publications

References 37 publications

Quantum Cascade Phenomenon inBi2Sr2CaCu2O8+δSingle Crystals

Quantum Cascade Phenomenon inBi2Sr2CaCu2O8+δSingle Crystals

Single intrinsic Josephson junction with double-sided fabrication technique

Acid etching process for fabrication of Bi2Sr2CaCu2O8+x stack

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