Elastic properties of flux lattices in anisotropic high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">T</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>superconductors

Vg, Kogan; Lj, Campbell

doi:10.1103/physrevlett.62.1552

Cited by 131 publications

(44 citation statements)

References 7 publications

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“…15,29 In anisotropic superconductors, shear moduli are different for different directions. 30 Accordingly, the strength of pinning has variation with direction, which is the major cause of the change in the strength of the peak effect for two directions. The angular dependence of the peak effect may be important in this compound, and it will be a future study.…”

Section: Resultsmentioning

confidence: 99%

Anisotropic vortex pinning in the layered intermetallic superconductor CaAlSi

et al. 2003

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We have studied anisotropic magnetic properties of layered intermetallic superconductor CaAlSi with moderate anisotropy. Near the upper critical field there is a prominent peak effect for H͉͉c at low temperatures and it becomes weaker for H͉͉ab. The estimated correlation length L c suggests the presence of three-dimensional collective pinning around the peak effect. The critical current densities for H͉͉c and H͉͉ab have been extracted and compared. Flux pinning mechanism in CaAlSi is anisotropic. Collective core pinning is observed for H͉͉c whereas there is a signature of deviation from it for H͉͉ab. The vortex phase diagram, including the upper critical field, irreversibility field, and peak field, has been studied. The thermodynamic critical field and Ginzburg-Landau parameter have been estimated from the equilibrium magnetization. The nature of scaling of the maximum pinning force densities with the thermodynamic critical field has been discussed. The temperature dependence of London penetration depth is consistent with single fully gapped state in CaAlSi.

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Section: Resultsmentioning

confidence: 99%

Anisotropic vortex pinning in the layered intermetallic superconductor CaAlSi

et al. 2003

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“…We may assume that the current required to induce the onset of plastic motion is predominantly determined by the hard-axis shear modulus c ⊥ 66 (θ) = c 0 66 /ε θ [32], where ε θ = cos 2 θ + ε 2 sin 2 θ , ε 2 is the mass anisotropy ratio defined as ε −2 ≡ (m c /m ab ) [23,33], and c 0 66…”

Section: Bulk Pinning and The Onset Of Plastic Motionmentioning

confidence: 99%

Current-driven vortex dynamics in untwinned superconducting single crystals

Jiang

Yeh

Tombrello

et al. 1997

J. Phys.: Condens. Matter

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Abstract. Current-driven vortex dynamics of type-II superconductors in the weak-pinning limit is investigated by quantitatively studying the current-dependent vortex dissipation of an untwinned YBa 2 Cu 3 O 7 single crystal. For applied current densities (J ) substantially larger than the critical current density (J c ), non-linear resistive peaks appear below the thermodynamic firstorder vortex-lattice melting transition temperature (T M ), in contrast to the resistive hysteresis in the low-current limit (J < J c ). These resistive peaks are quantitatively analysed in terms of the current-driven coherent and plastic motion of vortex bundles in the vortex-solid phase, and the non-linear current-voltage characteristics are found to be consistent with the collective flux-creep model. The effects of high-density random point defects on the vortex dynamics are also investigated via proton irradiation of the same single crystal. Neither resistive hysteresis at low currents nor peak effects at high currents are found after the irradiation. Furthermore, the current-voltage characteristics within the instrumental resolution become completely ohmic over a wide range of currents and temperatures, despite theoretical predictions of much larger J c -values for the given experimental variables. This finding suggests that the vortex-glass phase, a theoretically proposed low-temperature vortex state which is stabilized by point disorder and has a vanishing resistivity, may become unstable under applied currents significantly smaller than the theoretically predicted J c . More investigation appears necessary in order to resolve this puzzling issue.

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“…A uniform displacement u x = ǫx, u y = −ǫy (ǫ ≪ 1 is a constant) is of a special interest: it is this deformation that transforms the square above H ✷ into a rhombus for B < H ✷ . This deformation was named "squash" [20], so that c s is the squash modulus. Since this is a second order phase transition, c s must vanish at B = H ✷ .…”

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Effect of Fluctuations on Vortex Lattice Structural Transitions in Superconductors

Gurevich

Kogan

2001

Phys. Rev. Lett.

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The rhombic-to-square transition field H✷(T ) for cubic and tetragonal materials in fields along [001] is evaluated using the nonlocal London theory with account of thermal vortex fluctuations. Unlike extended Ginzburg-Landau models, our approach shows that the line H✷(T ) and the upper critical field Hc2(T ) do not cross due to strong fluctuations near Hc2(T ) which suppress the square anisotropy induced by the nonlocality. In increasing fields, this causes re-entrance of the rhombic structure in agreement with recent neutron scattering data on borocarbides.PACS numbers: 74.60. 74.60.Ge, 74.70.Dd Complex behavior of vortex lattices (VLs) even in cubic superconductors like Nb has been known for a long time [1]. Recent progress in understanding the evolution of VLs with the magnetic field H and temperature T became possible due to availability of large high quality crystals of borocarbides [2], which triggered a score of small-angle neutron scattering (SANS) [3][4][5], scanning tunneling [6,7], and decoration experiments [8]. Of a particular interest is the ubiquitous structural transition between rhombic and square VLs in increasing fields along the c axis of tetragonal borocarbides [3][4][5].For this case, the vortex repulsion is isotropic within the standard London and Ginzburg-Landau (GL) theories, so that vortices should always form the hexagonal Abrikosov lattice, which provides the maximum vortex spacing for a given flux density B/φ 0 (φ 0 is the flux quantum). There is no coupling between the VL and the crystal in these models; as a consequence, the VL orientation is arbitrary and no VL structural transitions are expected. A full microscopic theory of the mixed state contains this coupling, but involves self-consistent calculations of the gap and current distributions, a formidable task even for materials with the GL parameter κ ∼ 1 [9]. The situation simplifies in high-κ materials (like borocarbides), for which one can utilize a more transparent nonlocal London model [10]. Within this approach, the VL coupling to the crystal is provided by the basic nonlocal relation between the current density and the vector potential,where the kernel Q depends on the Fermi surface [10,11], the pairing symmetry [12], and the field orientation. Here, we consider cubic or tetragonal s-wave materials in fields along the c axis so that Q(r) has the square symmetry.The kernel Q(r) decays over the nonlocality range ρ = f (T, ℓ)ξ 0 , where ℓ is the mean-free path for nonmagnetic scatterers and ξ 0 is the BCS zero-T coherence length. The function f decreases slowly with T and is suppressed strongly by scattering [10,11]. The nonlocality adds to the intervortex interaction a short-range potential V (x, y) with the symmetry of the crystal. In the low field limit, V is irrelevant and the VL is triangular; still, V removes the orientational degeneracy and locks the VL onto certain crystal direction. With decreasing intervortex spacing a(B), the potential V drives the triangular VL into a square at a field H ✷ (T ). The transit...

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Elastic properties of flux lattices in anisotropic high-Tcsuperconductors

Cited by 131 publications

References 7 publications

Anisotropic vortex pinning in the layered intermetallic superconductor CaAlSi

Anisotropic vortex pinning in the layered intermetallic superconductor CaAlSi

Current-driven vortex dynamics in untwinned superconducting single crystals

Effect of Fluctuations on Vortex Lattice Structural Transitions in Superconductors

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