Phase diagram of optimally doped<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: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><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn><mml:mi math

Langan, R.M.; Gordeev, S.N.; Groot, P.A.J. de; Jansen, A. G. M.; Gagnon, R.; Taillefer, Louis

doi:10.1103/physrevb.58.14548

Cited by 16 publications

(8 citation statements)

References 37 publications

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“…[17][18][19] With raising ␦ in the region near optimal doping due to the increase in the density of oxygen vacancies, pinning disorder is enhanced whereas at the same time the elastic energy remains almost unchanged. 10 Consequently, as predicted in Refs. 17-19, a shift of the location of the B pl (T) line to lower field values should take place in agreement with our observations.…”

Section: B Phase Diagramsupporting

confidence: 60%

“…2 Indeed, such a melting transition has been observed in numerous experiments with a variety of techniques, and for clean samples has been established to be of the first order. [3][4][5][6][7][8][9][10] The mixed state in the phase diagram of the HTSC becomes even more complicated if one considers the presence of quenched disorder and its interplay with thermal fluctuations. As shown long ago the Abrikosov lattice is unstable to point disorder beyond the Larkin length.…”

Section: Introductionmentioning

confidence: 99%

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Transition from elastic to plastic vortex phase and its evolution with quenched disorder inYBa2Cu3O<

et al. 2000

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We report on a detailed investigation of history effects in the magnetic hysteresis of pure YBa 2 Cu 3 O y single crystals with various types and densities of pinning sites. A partial magnetization loop technique is employed that enables us to detect the point where topological disorder first invades the vortex system. Accordingly, studies of detwinned single crystals with very low densities of point defects reveal a transition in the mixed state of the superconductor that separates a dislocation-free Bragg glass from a highly disordered vortex phase. The transition line is identified in the field-temperature phase diagram and found to lie in the vicinity of the onset of the second magnetization peak. The effect of decreasing oxygen stoichiometry in the studied region (6.550рyр6.999) is the shift of this boundary to lower fields, and its final disappearance for high values of the oxygen deficiency in agreement with theoretical predictions. Above the transition metastable topological defects proliferate in the vortex lattice resulting in prominent history effects in the critical current. The last diminish at high enough fields for low oxygen concentrations near optimal doping, an effect not seen for samples close to the stoichiometric state. We also study the influence of extended defects and find that a low density of twin boundaries does not affect the Bragg glass significantly. However, a high concentration of twins as well as low densities of columnar defects are shown to suppress the transition and eliminate the memory effects.

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Section: B Phase Diagramsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Transition from elastic to plastic vortex phase and its evolution with quenched disorder inYBa2Cu3O<

et al. 2000

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“…Large thermal energy would help overcome the effects of pinning centers in both cases, however, the FC state being more (macroscopically) uniform eventually produces a better ordered FLL with a larger correlation volume V c of the Larkin domain (than that in the ZFC case). We note that Kokkaliaris et al [18] have recently reported that in an untwinned YBCO crystal, which displays the phenomenon of a broad second magnetization peak (to be designated as H s p ) at high fields and lower temperatures,…”

Section: History Effects In χ′(T ) Behaviormentioning

confidence: 72%

“…The detailed characteristics of the evolution of the anomalous variation in J c across the (H,T) region of the second magnetization peak and that of the conventional peak effect are far from being understood in the context of a variety of HTSC systems [14][15][16][17][18]. In contrast, in the conventional low T c superconductors (LTSC) with considerably smaller (but often not negligible) thermal fluctuations, a PE near the normal state boundary (H c2 line) is a common occurrence over the entire field-temperature regime [19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Amorphization of vortex matter and indication of a reentrant peak effect in YBa2Cu3O7-δ

et al. 2000

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The peak effect (PE) has been observed in a twinned crystal of YBa 2 Cu 3 O 7−δ for H c in the low field range, close to the zero field superconducting transition temperature (T c (0)) . A sharp depinning transition succeeds the peak temperature T p of the PE. The PE phenomenon broadens and its internal structure smoothens out as the field is increased or decreased beyond the interval between 250 Oe and 1000 Oe. Moreover, the PE could not be observed above 10 kOe and below 20 Oe. The locus of the T p (H) values shows a reentrant characteristic with a nose like feature located at T p (H)/T c (0)≈0.99 and H≈100 Oe (where the FLL constant a 0 ≈penetration depth λ). The upper part of the PE curve (0.5 kOe

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“…A reduction in the oxygen content has three major effects: first there are changes in the density of current carriers leading to a modification in the onset of the transition temperature (T c ) and magnetic penetration depth [2]. The second effect is that oxygen depletion increases the number of point defects [3]. Also the anisotropy of the YBCO crystal can be controlled by the oxygen content, weakening the coupling between Cu±O layers, driving the system more two dimensionally [4 to 6].…”

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confidence: 99%

Decrease of Bulk Pinning Strength in Deoxygenated YBCO Single Crystals

Moreno

Bekeris

2000

phys. stat. sol. (b)

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We measured the first and third harmonics of the complex ac susceptibility in YBCO single crystals with different oxygen contents (6.5 ≤ x ≤ 7). The amplitude of the ac field was varied in presence of an external dc field both applied parallel to the c‐axis of the crystals. We give evidence that deoxygenation leads to a reduction of the bulk pinning strength and consequently to a stronger contribution of geometrical barriers. These results support the recently reported investigations showing that deoxygenation makes the YBCO crystals more anisotropic reducing the effective bulk pinning for quasi‐two‐dimensional vortices. We also show measurements for the same crystals with the ac field applied perpendicular to the c‐axis.

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Phase diagram of optimally dopedYBa2Cu3O7

Cited by 16 publications

References 37 publications

Transition from elastic to plastic vortex phase and its evolution with quenched disorder inYBa2Cu3O<

Transition from elastic to plastic vortex phase and its evolution with quenched disorder inYBa2Cu3O<

Amorphization of vortex matter and indication of a reentrant peak effect in YBa2Cu3O7-δ

Decrease of Bulk Pinning Strength in Deoxygenated YBCO Single Crystals

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