Anisotropic superconductivity in CaAlSi

Ghosh, Ajay; Hiraoka, Yoshihiko; Tokunaga, Masashi; Tamegai, T.

doi:10.1016/s0921-4534(03)01238-3

Cited by 6 publications

(4 citation statements)

References 17 publications

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“…The signal saturates at the level corresponding to the normal-state skin depth, thus providing additional information -contact-less measurements of the resistivity above the transition. We find 45 µΩ•cm and 33 µΩ•cm for 6.2 K and 7.3 K, respectively, which is in an agreement with direct measurements on single crystals, which found 36 µΩ•cm on higher T c sample [18,19]. On the contrary, when λ ab (T ) is plotted versus reduced temperature T /T c , the curves for two samples coincide (no normalization was done for the y−axis).…”

supporting

confidence: 89%

“…Measurements of the field dependence of the penetration depth in the vortex state also show a difference between the two sets of samples, as do measurements taken with different field orientations relative to the c−axis. Of particular interest is the variation of the second critical field and the so-called peak effect [9,14,15,18,19]. Tunnel-diode studies of these properties will be reported elsewhere.…”

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confidence: 99%

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Anisotropics-wave superconductivity in CaAlSi single crystals from penetration depth measurements

et al. 2006

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In-and out-of-plane London penetration depths were measured in single crystals CaAlSi ( Tc = 6.2 K and 7.3 K) using a tunnel-diode resonator. A full 3D BCS analysis of the superfluid density is consistent with a prolate spheroidal gap, with a weak-coupling BCS value in the ab-plane and stronger coupling along the c−axis. The gap anisotropy was found to significantly decrease for higher Tc samples.

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confidence: 89%

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confidence: 99%

Anisotropics-wave superconductivity in CaAlSi single crystals from penetration depth measurements

et al. 2006

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“…It is clear that the cusp-like anomaly of H c2 (y) is independent of the criterion to determine H c2 . We have also confirmed that the same anomalies appears when we determine H c2 (y) using magnetic permeability [10]. To explain the anomalous H c2 (y) the presence of the non-superconducting layer to decouple superconductivity is required.…”

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confidence: 73%

Anisotropic superconductivity in layered silicides

Rachi

Kumashiro

Fukuoka

et al. 2006

Science and Technology of Advanced Materials

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CaAlSi is a layered silicide with the AlB 2 -structure and shows superconductivity below 7.7 K. The angular dependence of the upper critical field, H c2 (y), in CaAlSi shows a cusp-like anomaly, suggesting the presence of decoupled two-dimensional superconducting layers. Concomitant with this feature, a strong lattice modulation along the c-axis exists in this material. On the other hand, H c2 (y) in CaGaSi is well fitted by the anisotropic Ginzburg-Landau (GL) model, and the superstructure along the c-axis is absent. In order to get some insight into the origin of the anomalous H c2 (y) in CaAlSi, we have performed magneto-optical observations of the vortex penetration for fields applied parallel and perpendicular to the c-axis. Vortices are found to penetrate the crystal inhomogeneously when the field is applied perpendicular to the c-axis, indicating the presence of macroscopic inhomogeneities in CaAlSi. We have also grown single crystals of CaAl 1Àx Ga x Si and studied the evolution of anomalous H c2 (y) and the lattice modulation along the c-axis. With increasing Ga content in CaAl 1Àx Ga x Si, the superstructure along the c-axis survives up to x ¼ 0.2, although the anomaly in H c2 (y) is strongly suppressed. It may suggest irrelevance of the two features, although it seems to be closely correlated in CaAlSi and CaGaSi. Possible scenarios for the appearance of the anomalous H c2 (y) are proposed. r

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“…The onset critical temperature is 6.0 K with a transition width of 0.2 K and the residual resistivity ratio of 2.7. 17 The hysteresis curves at various temperatures are shown in Figs. 1͑a͒ and 1͑b͒ for H͉͉c and HЌc, respectively.…”

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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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Anisotropic superconductivity in CaAlSi

Cited by 6 publications

References 17 publications

Anisotropics-wave superconductivity in CaAlSi single crystals from penetration depth measurements

Anisotropics-wave superconductivity in CaAlSi single crystals from penetration depth measurements

Anisotropic superconductivity in layered silicides

Anisotropic vortex pinning in the layered intermetallic superconductor CaAlSi

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