Low- or high-angle Ar ion-beam etching to create ramp-type Josephson junctions

Verbist, K.; Lebedev, Oleg I.; Tendeloo, Gustaaf Van; Verhoeven, M.A.J.; Rijnders, Augustinus J.H.M.; Blank, Dave H.A.

doi:10.1088/0953-2048/9/11/009

Cited by 10 publications

(3 citation statements)

References 11 publications

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“…To properly exploit material science recipes, technical steps are also of great importance. For instance, high-angle ion-beam etching [225] or a wet etching step in bromine solution in ethanol before barrier deposition [226], have proved to be of some help to reproducibly obtain the desired slope angle and step in the ramp geometry. Due to the complexity and variety of the materials science issues involved, it is quite difficult to draw a comprehensive picture of the physics of the junctions with artificial barriers.…”

Section: Junctions With An Artificial Barriermentioning

confidence: 99%

Weak links in high critical temperature superconductors

Tafuri¹,

2005

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The traditional distinction between tunnel and highly transmissive barriers does not currently hold for high critical temperature superconducting Josephson junctions, both because of complicated materials issues and the intrinsic properties of high temperature superconductors (HTS). An intermediate regime, typical of both artificial superconductorbarrier-superconductor structures and of grain boundaries, spans several orders of magnitude in the critical current density and specific resistivity. The physics taking place at HTS surfaces and interfaces is rich, primarily because of phenomena associated with d-wave order parameter (OP) symmetry. These phenomena include Andreev bound states, the presence of the second harmonic in the critical current versus phase relation, a doubly degenerate state, time reversal symmetry breaking and the possible presence of an imaginary component of the OP. All these effects are regulated by a series of transport mechanisms, whose rules of interplay and relative activation are unknown. Some transport mechanisms probably have common roots, which are not completely clear and possibly related to the intrinsic nature of high-T C superconductivity. The d-wave OP symmetry gives unique properties to HTS weak links, which do not have any analogy with systems based on other superconductors. Even if the HTS structures are not optimal, compared with low critical temperature superconductor Josephson junctions, the state of the art allows the realization of weak links with unexpectedly high quality quantum properties, which open interesting perspectives for the future. The observation of macroscopic quantum tunnelling and the qubit proposals represent significant achievements in this direction. In this review we attempt to encompass all the above aspects, attached to a solid experimental basis of junction concepts and basic properties, along with a flexible phenomenological background, which collects ideas on the Josephson effect in the presence of d-wave pairing for different types of barriers.

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Section: Junctions With An Artificial Barriermentioning

confidence: 99%

Weak links in high critical temperature superconductors

Tafuri¹,

2005

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“…We concentrate ourselves here on the special features in the PrBCGaO barrier layer. Other aspects of the microstructure of these JJs have been reported in [11,12]. No special features were found at the interfaces or inside the superconducting layers responsible for the abnormal behaviour of JJs with substitution levels x = 0.7 or 1 for the barrier layer.…”

Section: Ramp-type Jjs With Prbcgao Barrier Layersmentioning

confidence: 76%

Microstructure of Josephson junctions in relation to their properties

Verbist

Lebedev

Verhoeven

et al. 1998

Supercond. Sci. Technol.

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The microstructure of various types of Josephson junctions is investigated with cross-sectional (CS) high-resolution electron microscopy (HREM). Special specimen preparation techniques, to facilitate the CS investigation, are discussed in the first part. Examples are shown of specially produced arrays of junctions and of the focused ion beam thinning technique allowing us to investigate specific measured junctions. Ramp-type junctions with (PrBCGaO) barrier layers are discussed in more detail in the second part. The microstructure of PrBCGaO (0.1 < x < 1.0) thin films, barrier layers and bulk material is studied by HREM. Thin barrier layers with contain a Ga-rich intergrowth, never observed before in YBCO-type structures. Ga-rich inclusions in single thin films exhibit a similar structure. In addition, diffusion of Ga in the ion-etched substrate surface region was observed. The observed segregation of Ga from the PrBCGaO barrier layer explains the observed junction properties.

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“…Hence, the structure, interfaces, and microstructural defects of these ramp-type JJs were studied by HREM and ED. 9,10 In this letter we concentrate on the particularities in the PrBCGaO barrier layer. The junction, discussed here have a ramp angle of 20°-28°and a barrier layer thickness of 10-30 nm.…”

mentioning

confidence: 99%

Ga segregation in DyBa2Cu3O7−δ/PrBa2Cu3−xGaxO7−δ/DyBa2Cu3O7−δ ramp-type Josephson junctions

Verbist

Lebedev

Tendeloo

et al. 1997

Applied Physics Letters

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Ramp-type Josephson junctions with highly doped PrBa2Cu3−xGaxO7−δ barrier layers (x=0.7, 1.0) have been investigated by high-resolution electron microscopy. A Ga-rich intergrowth and Ga diffusion in the ion-milled SrTiO3 substrate are observed. The Ga segregation is responsible for the deviating electrical behavior as expected from extrapolation of low doping levels (x=0.1–0.4). The Ga diffusion in the ion-milled substrate, and possibly in the base electrode, may hamper Josephson junction fabrication using substituted REBa2Cu3O7−δ materials (RE=rare earth).

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Low- or high-angle Ar ion-beam etching to create ramp-type Josephson junctions

Cited by 10 publications

References 11 publications

Weak links in high critical temperature superconductors

Weak links in high critical temperature superconductors

Microstructure of Josephson junctions in relation to their properties

Ga segregation in DyBa2Cu3O7−δ/PrBa2Cu3−xGaxO7−δ/DyBa2Cu3O7−δ ramp-type Josephson junctions

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