Dimensional crossover field as a function of oxygen stoichiometry in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">YBa</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Cu</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow

Deak, J.; Hou, Lifang; Metcalf, P.; McElfresh, M.

doi:10.1103/physrevb.51.705

Cited by 38 publications

(17 citation statements)

References 12 publications

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“…Experiments on oxygen-deficient YBa 2 Cu 3 O y thin films [78,79] indicate that for applied magnetic fields currently attainable in a TF-µSR experiment (H = 80 kOe), the FLL remains 3D at low T , except perhaps in lightly doped samples. However, the dimensionality of the vortex system depends on the degree of sample disorder, which can cause pinning-induced misalignment of the pancake vortices that make up a vortex line.…”

Section: D Pancake Vorticesmentioning

confidence: 99%

Muon spin rotation studies of electronic excitations and magnetism in the vortex cores of superconductors

Sonier

2007

Rep. Prog. Phys.

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The focus of this article is on recent progress in muon spin rotation (µSR) studies of the vortex cores in type-II superconductors. By comparison of µSR measurements of the vortex-core size in a variety of materials with results from techniques that directly probe electronic states, the effect of delocalized quasiparticles on the spatial variation of field in a lattice of interacting vortices has been determined for both single-band and multi-band superconductors. These studies demonstrate the remarkable accuracy of what some still consider an exotic technique. In recent years µSR has also been used to search for magnetism in and around the vortex cores of high-temperature superconductors. As a local probe µSR is specially suited for detecting static or quasistatic magnetism having short-range or random spatial correlations. As discussed in this review, µSR experiments support a generic phase diagram of competing superconducting and magnetic order parameters, characterized by a quantum phase transition to a state where the competing order is spatially non-uniform.

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Section: D Pancake Vorticesmentioning

confidence: 99%

Muon spin rotation studies of electronic excitations and magnetism in the vortex cores of superconductors

Sonier

2007

Rep. Prog. Phys.

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“…From Eq. 1 and the relationship between δ and γ found by Deak et al [11] this would predict, at t=0, a value for θ 2 of 3…”

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confidence: 69%

“…Importantly the removal of oxygen from the chains does not increase pinning [7,8]. However, there is a definite increase in superconducting anisotropy with δ at larger values [9, 10], indeed Deak et al [11] indicate that the anisotropy more than doubles for δ > 0.2.Intrinsic vortex channelling along the a-b planes has previously been reported in optimally doped YBCO films grown on mis-cut (vicinal) substrates [12]. The development of the channelling minima in these measurements has been attributed to the appearance of a kinked (string/pancake) vortex state as the angle, θ, between the a-b planes and the applied field is reduced.…”

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confidence: 95%

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Effect of varying material anisotropy on critical current anisotropy in vicinal YBa2Cu3O7−δ thin films

Durrell

Evetts

Rössler

et al. 2003

Applied Physics Letters

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The high Tc cuprate superconductors are noted for their anisotropic layered structure, certain of these materials indeed tend toward the limit of a Lawrence-Doniach superconductor. However, YBa2Cu3O 7−δ has a smaller anisotropy than would be expected from its interlayer spacing. This is due to the cuprate chains in the structure. To investigate the influence of the chain oxygen on transport properties critical current versus applied field angle measurements were performed on fully oxygenated and de-oxygenated YBa2Cu3O 7−δ thin films and optimally oxygenated Y0.75Ca0.2Ba2Cu3O 7−δ thin films. The films were grown on 10• mis-cut SrTiO3 substrates to enable the intrinsic vortex channelling effect to be observed. The form of the vortex channelling minimum observed in field angle dependent critical current studies on the films was seen to depend on film oxygenation. The vortex channelling effect is dependent on a angular dependent cross-over to a string-pancake flux line lattice. The results obtained appear to be consistent with the prediction of Blatter et al. [Rev. Mod. Phys., 66 (4): 1125] that increased superconducting anisotropy leads to the kinked string-pancake lattice existing over a smaller angular range. [2,3,4,5] (the large uncertainty in the Bi 2 Sr 2 Ca 1 Cu 2 O 8+x value is due to the difficulty in measuring its c axis transport properties).The structure of YBCO contains 'cuprate chains' inside the blocking layers between the cuprate planes associated with superconductivity. In most cuprate superconductors the blocking layers act as an insulating charge reservoir, in YBCO however, the cuprate chains also have superconducting properties [6]. This is the feature of YBCO which leads to the lower anisotropy seen in YBCO as compared to that predicted on the basis of the interlayer spacing. The chain oxygen in YBCO is highly mobile, under doping or over doping of the material by moving the oxygenation away from δ ∼ 0.08 is associated with a reduction in T c . A reduced oxygenation level will, however, also increase the superconducting anisotropy of the material by disrupting the cuprate chains. Importantly the removal of oxygen from the chains does not increase pinning [7,8]. However, there is a definite increase in superconducting anisotropy with δ at larger values [9, 10], indeed Deak et al. [11] indicate that the anisotropy more than doubles for δ > 0.2.Intrinsic vortex channelling along the a-b planes has previously been reported in optimally doped YBCO films grown on mis-cut (vicinal) substrates [12]. The development of the channelling minima in these measurements has been attributed to the appearance of a kinked (string/pancake) vortex state as the angle, θ, between the a-b planes and the applied field is reduced. The pinning of vortex string elements against a Lorentz force directed parallel to the a-b planes is relatively weak. By using a vicinal geometry thin film it is The angle θ is that between the applied magnetic field and the a-b crystallographic planes. The angle φ is that of the rotation of ...

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“…The increase in anisotropic parameter by factor of 1.3-1.4 with increase of Zn content up to 4.3% is reported [15,17]. In the weakly anisotropic HTSC like YBCO, the temperature dependence of the decoupling field H 0 (H 0 = u 0 /dc 2 ) for under-doped samples has been reported [18] to have the similar power law dependence with the parameter m 2 varying in the range of 1.3-1.5, compared to theoretically predicted value of 2. The change in the anisotropic factor resulting from oxygen variations in the under-doped samples is 0.5 and is proposed to cause decrease in the decoupling field.…”

Section: Discussionmentioning

confidence: 93%