Observation of a Field-Driven Structural Phase Transition in the Flux Line Lattice in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>ErNi</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>B</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:math>

Eskildsen, M. R.; Gammel, P. L.; Barber, Bradley P.; Yaron, U.; Ramirez, A. P.; Huse, David A.; Bishop, David J.; Bolle, C. A.; Lieber, Charles M.; Oxx, S.; Sridhar, S.; Andersen, N.H.; Mortensen, K.; Canfield, Paul C.

doi:10.1103/physrevlett.78.1968

Cited by 132 publications

(76 citation statements)

References 11 publications

(15 reference statements)

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“…The gradual transition from the triangular to the square vortex lattice is also observed with increasing field. 23,43 As µSR and SANS experiments have begun on these materials, we expect that the d x 2 −y 2 -wave-like nature will be detected there.…”

Section: Summary and Discussionmentioning

confidence: 99%

Field dependence of the vortex structure ind-wave ands-wave superconductors

1999

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We study the vortex structure and its field dependence within the framework of the quasi-classical Eilenberger theory to find the difference between the d x 2 −y 2 -and s-wave pairings. We clarify the effect of the d x 2 −y 2 -wave nature and the vortex lattice effect on the vortex structure of the pair potential, the internal field and the local density of states. The d x 2 −y 2 -wave pairing introduces a fourfold-symmetric structure around each vortex core. With increasing field, their contribution becomes significant to the whole structure of the vortex lattice state, depending on the vortex lattice's configuration. It is reflected in the form factor of the internal field, which may be detected by small angle neutron scattering, or the resonance line shape of µSR and NMR experiments. We also study the induced s-and dxy-wave components around the vortex in d x 2 −y 2 -wave superconductors.

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Section: Summary and Discussionmentioning

confidence: 99%

Field dependence of the vortex structure ind-wave ands-wave superconductors

1999

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“…10. One of the interesting features of some borocarbides (R=Er, Lu, Y) is the vortex lattice (VL) with unusual square symmetry [11][12][13][14] observed in the mixed state for magnetic fields H directed along tetragonal c-axis at H > ∼ 1 kOe. Square symmetry of VL can be connected 11,8 with the anisotropy of the upper critical magnetic field H c2 (T ) observed in the ab-plane for LuNi 2 B 2 C. 8,9 Practically no anisotropy of H c2 (T ) was found for YNi 2 B 2 C, 6,9 although this compound is very similar to LuNi 2 B 2 C. The reason for the difference in the behavior of these two borocarbides is still unclear.…”

Section: Introductionmentioning

confidence: 99%

Hall effect inLuNi2B2Cand<

et al. 1999

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The Hall effect in LuNi2B2C and YNi2B2C borocarbides has been investigated in normal and superconducting mixed states. The Hall resistivity ρxy for both compounds is negative in the normal as well as in the mixed state and has no sign reversal below Tc typical for high-Tc superconductors. In the mixed state the behavior of both systems is quite similar. The scaling relation ρxy ∼ ρ β xx (ρxx is the longitudinal resistivity) was found with β = 2.0 and 2.1 for annealed Luand Y-based compounds, respectively. The scaling exponent β decreases with increasing degree of disorder and can be varied by annealing. This is attributed to a variation of the strength of flux pinning. In the normal state weakly temperature dependent Hall coefficients were observed for both compounds. A distinct nonlinearity in the ρxy dependence on field H was found for LuNi2B2C in the normal state below 40 K, accompanied by a large magnetoresistance (MR) reaching +90% for H = 160 kOe at T = 20 K. At the same time for YNi2B2C only linear ρxy(H) dependences were observed in the normal state with an approximately three times lower MR value. This difference in the normal state behavior of the very similar Lu-and Y-based borocarbides seems to be connected with the difference in the topology of the Fermi surface of these compounds.

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“…[5][6][7][8] This is not expected for the local model with isotropic intervortex interactions and thereby suggests the importance of considering electronic structure (or the Fermi surface) and the associated nonlocal corrections in the specific compound.…”

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Nonlocal effects and shrinkage of the vortex core radius inYNi2B2Cprobed by muon spin rotation

et al. 2002

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The magnetic field distribution in the vortex state of YNi2B2C has been probed by muon spin rotation (µSR). The analysis based on the London model with nonlocal corrections shows that the vortex lattice has changed from hexagonal to square with increasing magnetic field H. At low fields the vortex core radius, ρv(H), decreases with increasing H much steeper than what is expected from the √ H behavior of the Sommerfeld constant γ(H), strongly suggesting that the anomaly in γ(H) primarily arises from the quasiparticle excitations outside the vortex cores.74.60. Ec, 76.75.+i The recent studies of the flux-line lattice (FLL) state in ordinary s-wave superconductors have revealed that the electronic structure of vortices is much more complicated than that of a simple array of rigid cylinders containing normal electrons. One of the unexpected phenomena within this conventional model is the non-linearity in the magnetic field dependence of the Sommerfeld constant γ(H) (electronic specific heat coefficient) observed in CeRu 2 1 , NbSe 2 2 , and YNi 2 B 2 C 2 . According to the above simple model where the quasiparticle excitations are confined within the cores of vortices (with a radius ξ) in s-wave superconductors, one would expect that γ(H) is proportional to the number of vortices per unit cell and thus to the applied magnetic field H. However, experiments have revealed that this is not the case for any of the above compounds. 1,2 Instead, they find a field dependence like γ(H) ∝ √ H which is expected for d-wave superconductors having more extended quasiparticle excitations along nodes in the energy gap. The recent study on the effect of doping in YNi 2 B 2 C and NbSe 2 indicates that the anomalous field dependence is observed only in the clean limit 2 , suggesting the importance of nonlocal effects in understanding the field dependence of γ(H). Moreover, it has been reported that the vortex core radius depends on applied magnetic field and shrinks at higher fields in NbSe 2 3 and in CeRu 2 4 .Another complication especially for borocarbides (RNi 2 B 2 C, R = rare earth) is that a square FLL is formed in some of these compounds at high magnetic fields, whereas a hexagonal FLL is realized at low fields. 5-8 This is not expected for the local model with isotropic intervortex interactions and thereby suggests the importance of considering electronic structure (or the Fermi surface) and the associated nonlocal corrections in the specific compound.We report on µSR measurements of the magnetic field dependence of theâ-b magnetic penetration depth λ, the effective vortex core radius ρ v , and the apex angle of the FLL θ in single crystalline YNi 2 B 2 C. We demonstrate that the proper reconstruction of the field profile with a square FLL is obtained from the µSR spectra only when the nonlocal corrections are considerred. 9 The field dependence of λ turned out to be linear over the entire magnetic field range of observation. More importantly, it was found that ρ v shrinks sharply with increasing magnetic field and levels ...

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Observation of a Field-Driven Structural Phase Transition in the Flux Line Lattice inErNi2B2C

Cited by 132 publications

References 11 publications

Field dependence of the vortex structure ind-wave ands-wave superconductors

Field dependence of the vortex structure ind-wave ands-wave superconductors

Hall effect inLuNi2B2Cand<

Nonlocal effects and shrinkage of the vortex core radius inYNi2B2Cprobed by muon spin rotation

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