Enhancement of Bose-Glass Superconductivity in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>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>Cu</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn><mml:mo>−</mml:mo><mml:mi mathvariant="italic">δ</mml:mi></mm

Nakielski, G.; Rickertsen, A.; Steinborn, T.; Wiesner, J.; Wirth, G.; Jansen, A. G. M.; Kötzler, J.

doi:10.1103/physrevlett.76.2567

Cited by 35 publications

(30 citation statements)

References 27 publications

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“…4 and 5, have not shown any evidence of characteristic changes in the melting line at B ⌽ . [6][7][8][9] This state of affairs appears to support the original predictions by NV who found the phase boundary to be smooth through the matching field. However, there are several issues, both experimental and theoretical, that make the evidence less clear.…”

supporting

confidence: 70%

“…We measure the Bose-glass transition temperature T g as a function of magnetic-field component applied parallel to the columnar defect axis, H ʈ , and find T g highly sensitive to the perpendicular field components and to large ac driving field. In contrast to previous experiments, [6][7][8][9] we observe a 30% change in the slope of the melting line at the matching field. However, rather than the cusplike feature predicted by recent theories, we find a knee joining two nearly linear segments above and below B ⌽ .…”

contrasting

confidence: 55%

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Signature of the matching field in Bose-glass melting of untwinnedYBa2Cu3O
Smith¹,
Jaeger²,
Rosenbaum³
et al. 1999
Phys. Rev. B
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7
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We map out the phase boundary separating the Bose-glass and vortex-liquid phases in an irradiated twin-free YBa 2 Cu 3 O 7Ϫ␦ single crystal. We take the phase boundary to be the temperature T g and magnetic field H at which the crystal begins to screen a small ac magnetic field, h ac . There is a significant change in slope dT g /dH of the phase boundary at the matching field B ⌽ (Ӎ0.5 T) indicating that interstitial vortices significantly weaken pinning in the Bose-glass state. There is also a pronounced peak in the slope dT g /dH just below B ⌽ at higher h ac . Both features disappear when the field is tilted away from the columns. ͓S0163-1829͑99͒51318-0͔Understanding the nature of the transition from vortex liquid to solid in the high-T c cuprates has been a challenge because of the important role played by microscopic disorder.1 Of particular interest is the case of correlated disorder produced by columnar defects. These defects, artificially created by the damage tracks from heavy ion irradiation, extend over large distances (m) and pin vortices much more effectively than ordinary point defects. Nelson and Vinokur 2 ͑NV͒ have mapped the statistical mechanics of vortices in the presence of columnar defects onto that of two-dimensional bosons in a random potential. They show the existence of a Bose-glass phase where vortices become localized on columnar defects. This phase is characterized by an infinite tilt modulus and by a vanishing linear resistivity at the transition temperature. A unique situation occurs at the matching field, B ⌽ , which is the magnetic field at which the number of vortices equals that of columnar defects. NV find that, at low temperatures, BϭB ⌽ coincides with a Mott insulator phase with infinite compressional modulus. Evidence for such a phase has been observed in recent experiments on magnetization relaxation. 3 The question we address here is to what extent B ⌽ also marks a special point at higher temperatures, along the melting line for the Bose glass.Experimental results so far, with the exception of Refs. 4 and 5, have not shown any evidence of characteristic changes in the melting line at B ⌽ . [6][7][8][9] This state of affairs appears to support the original predictions by NV who found the phase boundary to be smooth through the matching field. However, there are several issues, both experimental and theoretical, that make the evidence less clear. They involve the effect of residual disorder from twinning or point defects and, in particular, the necessary degree of alignment between the magnetic field direction and the columnar defect axis. This becomes important in light of recent theoretical approaches 10,11 which have shown that the melting line should exhibit a characteristic, cusplike feature at B ⌽ , i.e., a change of slope and curvature. In particular, it appears that this feature should persist in the experimentally important limit where the average defect spacing d is much less than the magnetic penetration depth and interactions involving many vortices become import...

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supporting

confidence: 70%

contrasting

confidence: 55%

Signature of the matching field in Bose-glass melting of untwinnedYBa2Cu3O
Smith¹,
Jaeger²,
Rosenbaum³
et al. 1999
Phys. Rev. B
15
0
7
1
View full text Add to dashboard Cite

show abstract

“…1 demonstrates that an external field as low as 0.1mT destroys the crossing of the phase angles, and that the positive, 'paraconductive' slope, dϕ/dω > 0, remains at all lower temperatures. This implies the destruction of true supercon-ductivity by very small external fields, which is in sharp contrast to YBa 2 Cu 3 O 7 , where 3D-ordering characterized by ϕ c = 75 0 (2 0 ), between zero field [13] and 19T [20] has been observed using the crossing point criterion. We regard this sensitivity of T c against externally induced vortices as a first indication of a lowered dimensionality.…”

mentioning

confidence: 94%

Two-dimensional fluctuations close to the zero-field transition ofBi2Sr2CaCu
Kötzler¹,
Kaufmann²
1997
Phys. Rev. B
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The ac-conductivity along the CuO2-layers of epitaxial films and single crystals of thicknesses 0.2µm≤ Lz ≤130µm reveals clear signatures for 2D-ordering. In particular, at Tc the screening length assumes the universal value LzΛT c /2νs predicted by the Kosterlitz-Thouless theory, which indicates that binding of long vortex strings nucleates long-range superconductivity in the present samples containing up to 10 5 CuO2-layers. Several details of the order-parameter dynamics remain unexplained.PACS numbers: 74.40.+k, 74.25.Fy, 74.72.Hs The layered structure of the high-T c oxide superconductors (HTSC) promotes the formation of topological exitations which may reduce T c to temperatures significantly below the mean-field value T c0 , where a finite Cooper-pair density n In order to provide a deeper insight into the ordering process in bulk (N ≫ 1) samples of the strongly layered HTSC Bi 2 Sr 2 CaCu 2 O 8 , where γ > ∼ 100, we present here a first study of the linear ac-conductivity σ(ω) in the highly conducting and fluctuating regime below T c0 . By scaling analyses, we determine static screening length λ 2 ± associated with superconducting and normal fluctuations above and below T c , respectively. For all temperatures above T c , λ 2 + provides quantitative evidence for 2D-ordering in the single crystals and the epitaxial film under study of thicknesses L z between 0.2µm and 130µm, and the dynamical shape of σ(ω) is described assuming 2D-fluctuations of the order parameter Ψ. At T c , the effective penetration depth 2λ 2 (T c )/L z agrees with the universal length associated with the KT transition. The high, universal value of the phase angle at T c , σ ′′ /σ ′ = 13.5 (1) 5 CuO 2 -planes, signatures of 3D-ordering appear only at temperatures below T c .Our inductive method for determining high ac conductivities from the measured linear magnetic susceptibility χ(ω) = χ ′ + iχ ′′ has been outlined before for bulk [14] and thin film [12] samples. Exact numerical relations between χ(ω) and σ(ω) = σ ′ + iσ ′′ were derived by E.H. Brandt for disks of arbitrary thickness [15], and using a complex inversion scheme, we evaluated σ(ω). We examine here a 0.2µm thick film epitaxially grown for SQUID fabrication [16] and crystalline discs of thicknesses between 13µm and 130µm, which were cleaved from the same crystal grown by L. Winkeler [17]. One of the great advantages of investigations of σ(ω) lies in the possibility of a precise determination of the onset for long-range superconductivity at the temperature where the frequency variation of the phase angle, d(σ ′′ /σ ′ )/dω, changes its sign [18].The first of such results for Bi 2 Sr 2 CaCu 2 O 8 are depicted in Fig.1 showing well defined intersections of the phase, i.e. d(σ ′′ /σ ′ )/dω = 0. Several novel features are seen. Despite the rather different T c 's of crystal and film, both attain there the same value of the phase angle, ϕ c ≡ arctan(σ ′′ /σ ′ ) Tc = 85.9 0 (8), in zero magnetic field. Since we observed the same value also on many other Bi 2 Sr 2 CaCu 2 O 8 ...

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“…They find a sharp phase transition between a high-temperature vortex liquid of delocalized and entangled vortex lines and a low temperature Bose glass dominated by the spatial disorder in the columnar defect distribution. The predictions of scaling theory [5,[7][8][9] have been tested [10][11][12][13][14][15][16][17][18][19] by measuring the vortex mobility subjected to a driving current at the approach to the glass transition temperature, T BG . These experiments vary widely on values for the critical exponents and on the angular dependence of T BG .…”

Section: (Received 3 December 1999)mentioning

confidence: 99%

Vortex Flow and Transverse Flux Screening at the Bose Glass Transition

et al. 2000

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We study the vortex phase diagram in untwinned YBCO crystals with columnar defects. These randomly distributed defects are expected to induce a "Bose glass" phase of localized vortices exhibiting a vanishing resistance and Meissner effect for magnetic fields H Ќ transverse to the columns. We directly observe the transverse Meissner effect using a Hall probe array. As predicted, the Meissner state breaks down at temperatures T s that decrease linearly as H Ќ increases. However, T s lies far below the conventional melting temperature T m determined by a vanishing resistivity, suggesting a regime where vortices are effectively localized even when rotated off the columnar defects.PACS numbers: 74.60. Ge, 74.25.Bt Weak pinning, large anisotropy, and prodigious thermal fluctuations in high temperature superconductors permit magnetic vortices to exist in a liquid phase which flows easily in response to an external current [1]. This technologically undesirable state of finite electrical resistance is quelled only at sufficiently low temperatures when vortex-vortex interactions precipitate a solid phase [2][3][4]. Columnar defects, a form of strong disorder correlated across many CuO 2 planes, serve as an effective strategy to bolster the constraining effects of the interaction potential, localizing the vortices on the disordered array of columns. The resulting "Bose glass" phase [5] exhibits two characteristic signatures: a diverging vortex viscosity leading to a zero resistance state, as well as a diverging tilt modulus resulting in vortex alignment with the columns even as the external magnetic field rotates. A large rotation of the external field, however, will melt the glass at fixed temperature. We monitor both the onset of a resistive response (vortex mobility) and the onset of transverse flux penetration (vortex alignment). In contrast to theory, we find that these two events yield widely different demarcations for the Bose glass phase.Amorphous columnar tracks created by heavy ion bombardment of cuprate superconductors are of nearly optimal size and geometry to pin vortices over their entire length. Thermal excitations, however, permit some segment of a vortex line to wander off its pinning site. Nelson and Vinokur [5] have mapped this statistical mechanics problem onto the quantum mechanical problem of two-dimensional bosons in the presence of point disorder [6]. They find a sharp phase transition between a high-temperature vortex liquid of delocalized and entangled vortex lines and a low temperature Bose glass dominated by the spatial disorder in the columnar defect distribution. The predictions of scaling theory [5,[7][8][9] have been tested [10][11][12][13][14][15][16][17][18][19] by measuring the vortex mobility subjected to a driving current at the approach to the glass transition temperature, T BG . These experiments vary widely on values for the critical exponents and on the angular dependence of T BG . We consider an additional prediction of the theory, that below

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Enhancement of Bose-Glass Superconductivity inYBa2Cu3O7−δ

Cited by 35 publications

References 27 publications

Signature of the matching field in Bose-glass melting of untwinnedYBa2Cu3O
Smith¹,
Jaeger²,
Rosenbaum³
et al. 1999
Phys. Rev. B
15
0
7
1
View full text Add to dashboard Cite

Signature of the matching field in Bose-glass melting of untwinnedYBa2Cu3O
Smith¹,
Jaeger²,
Rosenbaum³
et al. 1999
Phys. Rev. B
15
0
7
1
View full text Add to dashboard Cite

Two-dimensional fluctuations close to the zero-field transition ofBi2Sr2CaCu
Kötzler¹,
Kaufmann²
1997
Phys. Rev. B
Self Cite
8
1
8
0
View full text Add to dashboard Cite

Vortex Flow and Transverse Flux Screening at the Bose Glass Transition

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Enhancement of Bose-Glass Superconductivity inYBa2Cu3O7−δ

Cited by 35 publications

References 27 publications

Signature of the matching field in Bose-glass melting of untwinnedYBa2Cu3OSmith1, Jaeger2, Rosenbaum3 et al. 1999Phys. Rev. B15071View full textAdd to dashboardCite

Signature of the matching field in Bose-glass melting of untwinnedYBa2Cu3OSmith1, Jaeger2, Rosenbaum3 et al. 1999Phys. Rev. B15071View full textAdd to dashboardCite

Two-dimensional fluctuations close to the zero-field transition ofBi2Sr2CaCuKötzler1, Kaufmann2 1997Phys. Rev. BSelf Cite8180View full textAdd to dashboardCite

Vortex Flow and Transverse Flux Screening at the Bose Glass Transition

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About

Signature of the matching field in Bose-glass melting of untwinnedYBa2Cu3O
Smith¹,
Jaeger²,
Rosenbaum³
et al. 1999
Phys. Rev. B
15
0
7
1
View full text Add to dashboard Cite

Signature of the matching field in Bose-glass melting of untwinnedYBa2Cu3O
Smith¹,
Jaeger²,
Rosenbaum³
et al. 1999
Phys. Rev. B
15
0
7
1
View full text Add to dashboard Cite

Two-dimensional fluctuations close to the zero-field transition ofBi2Sr2CaCu
Kötzler¹,
Kaufmann²
1997
Phys. Rev. B
Self Cite
8
1
8
0
View full text Add to dashboard Cite