Properties of normal metal/dielectric/high-Tc junctions obtained by in-situ oxidation

Racah, D.; Deutscher, G.

doi:10.1016/0921-4534(96)00067-6

Cited by 14 publications

(8 citation statements)

References 18 publications

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“…20 It is, however, in complete disagreement with the tunneling results of the same group in NIS junctions where a gap value of 50 meV (T c Ϸ60 K) was found. 21 In some of our junctions with steeper edge slope (␣ ϭ50°) and voltages above the gap, we found series of peaks in the dynamic resistance that have a constant periodicity. This is expected to occur if these peaks are due to either Tomasch oscillations at energies significantly higher than the gap or McMillan-Rowell oscillations.…”

mentioning

confidence: 76%

Measurements ofΔandvFfrom Andreev reflections and McMillan-Rowell oscillations in edge junctions of
Nesher
¹
,
Koren
²

1999
Phys. Rev. B
41
4
38
1
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We report measurements of dynamic resistance of high quality oxygen deficient SNS edge junctions with YBa 2 Cu 3 O 6.6 (T c ϭ60 K) as the superconductor ͑S͒ and YBa 2 Cu 2.55 Fe 0.45 O y as the barrier ͑N͒. Below the gap a series of peaks in the dynamic resistance is identified as due to multiple Andreev reflections in the barrier (V n ϭ2⌬/en), while above the gap, the peaks are attributed to McMillan-Rowell oscillations (⌬V ϭhv F Ј /4ed N ). Analysis of the subgap series in the 60 K YBa 2 Cu 3 O 6.6 yields a gap value ⌬ aϪb of 16 Ϯ1.5 meV, and a coupling constant 2⌬/kT c of 6.2Ϯ0.5. The McMillan-Rowell series yield the renormalized Fermi velocity of quasiparticles in the barrier v F Ј ϭ(1.5Ϯ0.1)ϫ10 7 cm/sec. ͓S0163-1829͑99͒15233-0͔ Tunneling spectroscopy in NIS or SIS junctions is an important tool in the study of the high-T c superconductors. It can yield the density of states of the superconductor, the symmetry of the order parameter, and other physical constants of the superconductor such as the gap energy and the Fermi velocity. A model of quasiparticles tunneling based on the Andreev reflection process was introduced by Blonder, Tinkham, and Klapwijk ͑BTK͒. 1 This model has been very successful in explaining tunneling results in junctions with low-T c superconductors which have isotropic s-wave symmetry. 2 More recently, this model was extended by Tanaka and Kashiwaya to include anisotropic d-wave superconductors. 3,4 Experimental results of scanning tunneling microscopy ͑STM͒ and point contact spectroscopy were found to be consistent with the predictions of this extended model. 5,6 However, additional important physical properties can be obtained from the investigation of SNS junction. Recently, we observed geometrical resonances in the dynamic conductance of this kind of junction, which were attributed to Tomasch oscillations in one of the superconducting electrodes ͑the S layer͒. 7 This indicates that the interfaces in our edge junctions are sufficiently smooth to allow for the observation of this kind of interference effect.In the present study we continued to investigate the dynamic resistance of our SNS edge junctions with barriers of different thickness and properties. This time, we focus on geometrical resonances in the barrier of the junctions ͑the N layer͒. In these junctions the incoming and reflected quasiparticles at each of the NS interfaces, or the bare S surface, are interfering and producing multiple Andreev reflections below the gap, or McMillan-Rowell and Tomasch oscillations above the gap. 8-10 It should be noted here that generally a junction shows either Tomasch oscillations, multiple Andreev reflections, or McMillan-Rowell oscillations, depending on its specific parameters such as the barrier strength and thickness. In the multiple Andreev scattering process, an incoming electronlike quasiparticle is reflected from one of the NS interfaces as a holelike quasiparticle with an opposite momentum. The holelike quasiparticle can then undergo Andreev reflection from the other SN interface a...

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mentioning

confidence: 76%

Measurements ofΔandvFfrom Andreev reflections and McMillan-Rowell oscillations in edge junctions of
Nesher
¹
,
Koren
²

1999
Phys. Rev. B
41
4
38
1
View full text Add to dashboard Cite

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“…In both cases, the PCCO surface is exposed to ambient atmosphere for no more than a few minutes. It has been demonstrated in Al=YBa 2 Cu 3 O 7ÿ contacts that the aluminum counterelectrode takes oxygen from the cuprate, thus creating an oxide barrier [13]. A similar process occurs in PCCO=Pb contacts [14].…”

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confidence: 89%

Tunneling into the Normal State ofPr2−xCexCuO4

2005

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The temperature dependence of the tunneling conductance was measured for various doping levels of Pr(2-x)CexCuO4 using planar junctions. A normal state gap is seen at all doping levels studied, x=0.11 to x=0.19. We find it to vanish above a certain temperature T*. T* is greater than T(c) for the underdoped region and it follows T(c) on the overdoped side. This behavior suggests finite pairing amplitude above T(c) on the underdoped side.

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“…Tunneling experiments in planar SIS junctions made of thin films had also been done, with the transport current along either the c axis, 6,7 or the a-b plane. 8,9 The dynamic conductance of these junctions show similar tunneling spectra in both directions, possibly because of the rough interfaces in these junctions.…”

mentioning

confidence: 92%

“…In order to analyze these results, we used the BTK formalism, 9 which was extended to include d x 2 Ϫy 2-wave symmetry by Tanaka and Kashiwaya. 2,3 In a d x 2 Ϫy 2-wave superconductor the density of states ͑DOS͒ near the interface is affected by Andreev scattering of electronlike quasiparticles and holelike quasiparticles.…”

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confidence: 99%

Directional in-plane tunneling in oxygen-deficientYBa2Cu3O6.6<

Nesher

Koren

1999

Phys. Rev. B

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In-plane tunneling measurements of superconductor-insulator-superconductor ͑SIS͒-type oxygen-deficient edge junctions made of YBa 2 Cu 3 O 6.6 as the superconductor and YBa 2 Cu 2.55 Fe 0.45 O y as the barrier are reported. Two types of junctions were prepared in which transport is either along the ͑100͒ or the ͑110͒ direction. The dynamic conductance dI/dV shows a gaplike structure in the ͑100͒ junctions, while a zero-bias peak is observed in the ͑110͒ junctions. At energies below ϳ2.5⌬ 0 the results were found to be consistent with the Blonder, Tinkham, and Klapwijk model, extended by Tanaka and Kashiwaya to the case of d x 2 Ϫy 2-wave superconductivity. At higher energies the behavior of the dynamic conductance is explained as due to a self-heating effect inside the junction. ͓S0163-1829͑99͒04745-1͔

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Properties of normal metal/dielectric/high-Tc junctions obtained by in-situ oxidation

Cited by 14 publications

References 18 publications

Measurements ofΔandvFfrom Andreev reflections and McMillan-Rowell oscillations in edge junctions of
Nesher
¹
,
Koren
²

1999
Phys. Rev. B
41
4
38
1
View full text Add to dashboard Cite

Measurements ofΔandvFfrom Andreev reflections and McMillan-Rowell oscillations in edge junctions of
Nesher
¹
,
Koren
²

1999
Phys. Rev. B
41
4
38
1
View full text Add to dashboard Cite

Tunneling into the Normal State ofPr2−xCexCuO4

Directional in-plane tunneling in oxygen-deficientYBa2Cu3O6.6<

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Properties of normal metal/dielectric/high-Tc junctions obtained by in-situ oxidation

Cited by 14 publications

References 18 publications

Measurements ofΔandvFfrom Andreev reflections and McMillan-Rowell oscillations in edge junctions ofNesher1, Koren2 1999Phys. Rev. B414381View full textAdd to dashboardCite

Measurements ofΔandvFfrom Andreev reflections and McMillan-Rowell oscillations in edge junctions ofNesher1, Koren2 1999Phys. Rev. B414381View full textAdd to dashboardCite

Tunneling into the Normal State ofPr2−xCexCuO4

Directional in-plane tunneling in oxygen-deficientYBa2Cu3O6.6<

Contact Info

Product

Resources

About

Measurements ofΔandvFfrom Andreev reflections and McMillan-Rowell oscillations in edge junctions of
Nesher
¹
,
Koren
²

1999
Phys. Rev. B
41
4
38
1
View full text Add to dashboard Cite

Measurements ofΔandvFfrom Andreev reflections and McMillan-Rowell oscillations in edge junctions of
Nesher
¹
,
Koren
²

1999
Phys. Rev. B
41
4
38
1
View full text Add to dashboard Cite