Submicron YBa2Cu3Ox ramp Josephson junctions

Komissinski, P.V.; Högberg, Björn; Tzalenchuk, Alexander; Ivanov, Z. G.

doi:10.1063/1.1448176

Cited by 13 publications

(9 citation statements)

References 11 publications

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“…The conventional way to fabricate deep submicron biepitaxial Josephson junctions is to use electron beam lithography in combination with a hard mask and ion beam milling. This procedure, with amorphous carbon as hard mask, is well established and has been proven to work well for the realization of various kinds of submicron HTS Josephson junctions, for example ramp type, 17 bicrystal, 18 and biepitaxial. 19 In this work, we have fabricatated deep submicron Josephson junctions by the biepitaxial technique.…”

Section: A Conventional Nanostructuringmentioning

confidence: 99%

Noise properties of nanoscale YBa2Cu3O7−δJosephson

Gustafsson

Lombardi

2011

Phys. Rev. B

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We present electric noise measurements of nanoscale biepitaxial YBa 2 Cu 3 O 7−δ (YBCO) Josephson junctions fabricated by two different lithographic methods. The first (conventional) technique defines the junctions directly by ion milling etching through an amorphous carbon mask. The second (soft patterning) method makes use of the phase competition between the superconducting YBCO (Y123) and the insulating Y 2 BaCuO 5 (Y211) phase at the grain boundary interface on MgO (110) substrates. The voltage noise properties of the two methods are compared in this study. For all junctions (having a thickness of 100 nm and widths of 250-500 nm), we see a significant amount of individual charge traps. We have extracted an approximate value for the effective area of the charge traps from the noise data. From the noise measurements, we infer that the soft-patterned junctions with a grain-boundary (GB) interface manifesting a large c-axis tunneling component have a uniform barrier and a superconductor-insulator-superconductor (SIS) -like behavior. The noise properties of soft-patterned junctions having a GB interface dominated by transport parallel to the ab planes are in accordance with a resonant tunneling barrier model. The conventionally patterned junctions, instead, have suppressed superconducting transport channels with an area much less than the nominal junction area. These findings are important for the implementation of nanosized Josephson junctions in quantum circuits.

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Section: A Conventional Nanostructuringmentioning

confidence: 99%

Noise properties of nanoscale YBa2Cu3O7−δJosephson

Gustafsson

Lombardi

2011

Phys. Rev. B

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“…The submicron bridges were defined using again electron beam lithography based on a multilayer carbon/PMMA ͑polymethyl methacrylate͒ mask. 11,14,16,17 After exposing and developing the PMMA, the pattern was transferred first to an evaporated chromium film using lift off, then to the carbon layer using reactive ion etching. The patterned carbon layer will then act as a mask for the shaping of the YBCO film by Ar ion beam etching.…”

Section: Methodsmentioning

confidence: 99%

Submicron YBaCuO biepitaxial Josephson junctions: d-wave effects and phase dynamics

Stornaiuolo

Rotoli

Cedergren

et al. 2010

Journal of Applied Physics

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We report a systematic study of the transport properties of high critical temperature superconductor ͑HTS͒ biepitaxial Josephson junctions in the submicron range. Junction performances point to more uniform and reproducible devices and to better control of d-wave intrinsic properties. Outcomes promote novel insights into the transport mechanisms across grain boundaries and encourage further developments in the control of dissipation in HTS devices. The application of nanotechnology to HTS could be an additional tool to properly engineer the junction properties to match specific circuit design also in view of the integration into hybrid quantum circuits.

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“…[16][17][18][19] Rather, the behavior of some grain boundary junctions. [16][17][18][19][20] seems to be consistent with the phenomenological theory of Sigrist and Rice. 21 This certainly requires a rational explanation.…”

Section: Introductionmentioning

confidence: 99%

Current transport and the fluctuation of critical current in high-temperature superconductor interface-engineered Josephson junctions

et al. 2004

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The mechanisms of current transport in interface-engineered junctions (IEJs) with ramp-edge geometry were investigated to clarify the possible origin of the statistical fluctuation of the Josephson critical current. More than 1000 junctions with a ramp edge aligned either along the [100] or [110] axis of the high-temperature superconductor electrode were fabricated under various process conditions. These junctions exhibited a critical current density ranging from 10 2 to 10 6 A/cm 2 at 4.2 K while maintaining a magnetic field modulation of the critical current exceeding 80% without any indication of the peculiar effect of d-wave pairing symmetry. The junctions with a critical current density exceeding 10 4 A/cm 2 exhibited an appreciable amount of excess current that grew rapidly within an approximate voltage range of less than 5 mV. The critical current versus temperature characteristics of these junctions were found to be explained reasonably well by a superconductornormal-superconductor (SNS) junction model in the diffusive regime. This model is also consistent with our observation of a weak subharmonic gap structure due to multiple Andreev reflections. In addition, we found that the Josephson critical current ͑I c ͒ exhibited a good correlation with the differential resistance near 0 V, while the normal resistance defined at a current level of two to three times I c varied appreciably even for junctions with a similar I c . This indicates that another conduction channel with little contribution to the Josephson current coexists within the junctions. The dI / dV measurement for high resistance junctions revealed that resonant tunneling of quasiparticles through localized states in an insulating barrier constitutes this second conduction channel. All these results suggest that IEJs should be regarded as an array of microscopic SNS contacts embedded in an insulating barrier with random orientation. The fluctuation in the number of SNS contacts in a junction restricts the attainable minimum spread of the I c value.

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Submicron YBa2Cu3Ox ramp Josephson junctions

Cited by 13 publications

References 11 publications

Noise properties of nanoscale YBa2Cu3O7−δJosephson

Noise properties of nanoscale YBa2Cu3O7−δJosephson

Submicron YBaCuO biepitaxial Josephson junctions: d-wave effects and phase dynamics

Current transport and the fluctuation of critical current in high-temperature superconductor interface-engineered Josephson junctions

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