Observation of the lock-in transition in Tl2Ba2Ca1Cu2Ox

Janossy, B.; Graaf, Alexander de; Kes, P.H.; Kopylov, V. N.; Togonidze, T.G.

doi:10.1016/0921-4534(95)00158-1

Cited by 9 publications

(4 citation statements)

References 23 publications

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“…If it is energetically favorable and not impeded by pinning, the flux lines in this case will spontaneously switch into the ab-plane. This lock-in transition (Feinberg and Villard 1990, Theodorakis 1990, Feinberg and Ettouhami 1993b, Koshelev 1993) was observed in HTSC's by Steinmeyer et al (1994a, b), Vulcanescu et al (1994), andJanossy et al (1995) in mechanical torque experiments, and in an organic layered superconductor by Mansky et al (1993) from ac susceptibility. It means that the perpendicular component of the applied field should only penetrate above some critical angle, for |π/2 − Θ| ≥ (1 − N )B c1,z /B a , where N is the demagnetization factor.…”

Section: Josephson Stringsmentioning

confidence: 74%

The flux-line lattice in superconductors

1995

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Magnetic flux can penetrate a type-II superconductor in form of Abrikosov vortices (also called flux lines, flux tubes, or fluxons) each carrying a quantum of magnetic flux φ 0 = h/2e. These tiny vortices of supercurrent tend to arrange in a triangular flux-line lattice (FLL) which is more or less perturbed by material inhomogeneities that pin the flux lines, and in high-T c superconductors (HTSC's) also by thermal fluctuations. Many properties of the FLL are well described by the phenomenological Ginzburg-Landau theory or by the electromagnetic London theory, which treats the vortex core as a singularity. In Nb alloys and HTSC's the FLL is very soft mainly because of the large magnetic penetration depth λ: The shear modulus of the FLL is c 66 ∼ 1/λ 2 , and the tilt modulus c 44 (k) ∼ (1 + k 2 λ 2 ) −1 is dispersive and becomes very small for short distortion wavelength 2π/k ≪ λ. This softness is enhanced further by the pronounced anisotropy and layered structure of HTSC's, which strongly increases the penetration depth for currents along the c-axis of these (nearly uniaxial) crystals and may even cause a decoupling of two-dimensional vortex lattices in the Cu-O layers. Thermal fluctuations and softening may "melt" the FLL and cause thermally activated depinning of the flux lines or of the two-dimensional "pancake vortices" in the layers. Various phase transitions are predicted for the FLL in layered HTSC's. Although large pinning forces and high critical currents have been achieved, the small depinning energy so far prevents the application of HTSC's as conductors at high temperatures except in cases when the applied current and the surrounding magnetic field are small.

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Section: Josephson Stringsmentioning

confidence: 74%

The flux-line lattice in superconductors

1995

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“…The second deviation at low angles ͑small H z ͒, which is accompanied by irreversibility, has been previously addressed as a surface-barrier effect, or as a consequence of a lock-in transition. 12 The universal behavior depicted in Fig. 2 is one of the central results of this paper since it reflects the angular response of the vortex system: for the same value of H z applied at different angles, the equilibrium magnetic moment is the same.…”

mentioning

confidence: 99%

Equilibrium magnetization in heavy-ion-irradiatedBi2Sr2CaCu2
Drost
¹
,
Beek
²
,
Heijn
³

et al. 1998
Phys. Rev. B
27
6
21
0
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“…In high anisotropy materials lock-in studies, [4][5][6][7] the 2D character is so strong that the lock-in is present almost up to T c . However, the vicinity of the superconducting transition makes it difficult to observe the lock-in onset.…”

Section: Introductionmentioning

confidence: 99%

Vortex lock-in transition coinciding with the 3D to 2D crossover in YBa2Cu3O7

et al. 2012

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A vortex lock-in transition was directly detected by torque magnetometry in an overdoped YBa 2 Cu 3 O 7 single crystal of low anisotropy (≈ 7). The locked-in state was observed below the two-to three-dimensional crossover temperature T cr = 76 K, independently of extrinsic pinning effects, thanks to a high-quality clean crystal and the use of a vortex shaking technique. The lock-in effect is enhanced by decreasing temperature and increasing magnetic field. The shape of the torque signal as a function of the angle between the applied magnetic field and the crystallographic c axis is in very good agreement with the model developed by Feinberg and Ettouhami [Int. J. Mod. Phys. B 7, 2085 (1993)] for quasi-2D superconductors, despite the low anisotropy of the material.

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Observation of the lock-in transition in Tl2Ba2Ca1Cu2Ox

Cited by 9 publications

References 23 publications

The flux-line lattice in superconductors

The flux-line lattice in superconductors

Equilibrium magnetization in heavy-ion-irradiatedBi2Sr2CaCu2
Drost
¹
,
Beek
²
,
Heijn
³

et al. 1998
Phys. Rev. B
27
6
21
0
View full text Add to dashboard Cite

Vortex lock-in transition coinciding with the 3D to 2D crossover in YBa2Cu3O7

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Observation of the lock-in transition in Tl2Ba2Ca1Cu2Ox

Cited by 9 publications

References 23 publications

The flux-line lattice in superconductors

The flux-line lattice in superconductors

Equilibrium magnetization in heavy-ion-irradiatedBi2Sr2CaCu2Drost1, Beek2, Heijn3 et al. 1998Phys. Rev. B276210View full textAdd to dashboardCite

Vortex lock-in transition coinciding with the 3D to 2D crossover in YBa2Cu3O7

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Equilibrium magnetization in heavy-ion-irradiatedBi2Sr2CaCu2
Drost
¹
,
Beek
²
,
Heijn
³

et al. 1998
Phys. Rev. B
27
6
21
0
View full text Add to dashboard Cite