Experimental Evidence of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>s</mml:mi></mml:math>-Wave Superconductivity in Bulk<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>CaC</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:math>

Lamura, G.; Aurino, Mario; Cifariello, G.; Gennaro, Emiliano Di; Andreone, A.; Eméry, N.; Hérold, Claire; Marêché, J.F.; Lagrange, P.

doi:10.1103/physrevlett.96.107008

Cited by 72 publications

(84 citation statements)

References 24 publications

(41 reference statements)

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“…Magnetic penetration depth measurements on CaC 6 [39] suggest an s-wave pairing with a single uniform energy gap of ∆(0) = (1.79 ± 0.08) meV. These measurements are supported by Scanning Tunneling Spectroscopy [40], which shows that CaC6 has a single isotropic gap of 1.6 ± 0.2meV.…”

Section: Empirical Aspects Of the Superconducting Ground-state In Gicssupporting

confidence: 61%

“…This technique allows both structural and electronic studies of materials. Scanning Tunneling spectroscopy (SPS) was first explored for CaC6 [40] and provided a verification of the superconducting energy gap consistent with that obtained by [39,42]. However, the work [40] was unable to obtain atomic-resolution images of the sample.…”

Section: Empirical Aspects Of the Superconducting Ground-state In Gicsmentioning

confidence: 99%

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Superconductivity in graphite intercalation compounds

Smith

Weller

Howard

et al. 2015

Physica C: Superconductivity and its Applications

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The field of superconductivity in the class of materials known as graphite intercalation compounds has a history dating back to the 1960s [1,2]. This paper recontextualizes the field in light of the discovery of superconductivity in CaC6 and YbC6 in 2005. In what follows, we outline the crystal structure and electronic structure of these and related compounds. We go on to experiments addressing the superconducting energy gap, lattice dynamics, pressure dependence, and how this relates to theoretical studies. The bulk of the evidence strongly supports a BCS superconducting state. However, important questions remain regarding which electronic states and phonon modes are most important for superconductivity and whether current theoretical techniques can fully describe the dependence of the superconducting transition temperature on pressure and chemical composition.Corresponding author. Tel: +44 (0)7792954220 fax: +44 (0)20 7679 7145 e-mail address: mark.ellerby@ucl.ac.uk (Mark Ellerby).

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Section: Empirical Aspects Of the Superconducting Ground-state In Gicssupporting

confidence: 61%

Section: Empirical Aspects Of the Superconducting Ground-state In Gicsmentioning

confidence: 99%

Superconductivity in graphite intercalation compounds

Smith

Weller

Howard

et al. 2015

Physica C: Superconductivity and its Applications

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“…phonon contribution is present. This justifies the assumption that the superconductivity in CaC 6 can be described in the dirty limit [16] and agrees with the general specifics of the intercalation process, which includes the presence of a certain amount of disorder in the light metal (in this case: Ca) distribution [19]. The linewidth shows a slight anisotropy which decreases with decreasing temperature.…”

Section: B) Cesr In the Normal Statesupporting

confidence: 65%

“…Despite its much higher T c , CaC 6 can also be described as a classical BCS superconductor with an isotropic gap. The zero temperature gap value is ∼1.7 meV [15] [16]. The upper critical field, H c2 , shows a remarkable anisotropy with the zero temperature value changing between ∼0.4 T and ∼1.9 T, depending on the external magnetic field direction [17].…”

Section: Introductionmentioning

confidence: 95%

Electron spin dynamics of the superconductorCaC6probed by ESR

et al. 2008

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Conduction Electron Spin Resonance (CESR) was measured on a thick slab of CaC6 in the normal and superconducting state. Non-linear microwave absorption measurements in the superconducting state describe CaC6 as an anisotropic BCS superconductor. CESR data in the normal state characterize CaC6 as a three-dimensional (3D) metal. The analysis suggests that the scattering of conduction electrons is dominated by impurities and supports the description of superconductivity in the dirty limit. A surprising increase of the CESR intensity below Tc can not be explained by the theoretically predicted change in spin susceptibility. It is interpreted as a vortex enhanced increase of the effective skin depth. The study of the spin dynamics in the superconducting state and the discovery of the vortex enhanced increase of the skin depth poses a challenge to theory to provide a comprehensive description of the observed phenomena.

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“…Two relevant issues are the nature of the superconducting pairing mechanism and the symmetry of the order parameter. There is a mounting experimental evidence from different spectroscopic tools, London penetration depth [3], tunnelling [4], and specific heat [5], that the superconducting order parameter does follow a conventional s-wave symmetry, and presents a ratio 2∆(0)/k B T C -where ∆(0) is the zero temperature energy gap -close to the BCS prediction. In the electromagnetic response, the characteristic signature of a gapped superconductor is an exponential behaviour of the microwave absorption, represented by the surface resistance R S , at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Microwave losses of bulk CaC6

Cifariello¹,

Gennaro²,

Lamura³

et al. 2007

Physica C: Superconductivity and its Applications

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We report a study of the temperature dependence of the surface resistance R S in the graphite intercalated compound (GIC) CaC 6 , where superconductivity at 11.5 K was recently discovered. Experiments are carried out using a copper dielectrically loaded cavity operating at 7 GHz in a "hot finger" configuration. Bulk CaC 6 samples have been synthesized from highly oriented pyrolytic graphite. Microwave data allows to extract unique information on the quasiparticle density and on the nature of pairing in superconductors. The analysis of R S (T) confirms our recent experimental findings that CaC 6 behaves as a weakly-coupled, fully gapped, superconductor.

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Experimental Evidence ofs-Wave Superconductivity in BulkCaC6

Cited by 72 publications

References 24 publications

Superconductivity in graphite intercalation compounds

Superconductivity in graphite intercalation compounds

Electron spin dynamics of the superconductorCaC6probed by ESR

Microwave losses of bulk CaC6

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