Abstract
Superconducting CaC6 is found to exhibit two important pressure effects: (i) a large P-induced T c enhancement up to 15.1 K at 7.5 GPa, the highest T c value hitherto reported for graphite intercalated compounds; and (ii) a dramatic T c drop down to ~3 K at a critical pressure of ~9 GPa suggestive of a structural instability. We show that a combined electrical resistivity and x-ray diffraction study under high pressures provides a comprehensive account of both phenomena within the frame of the BCS theory in terms of a P-induced softening of the in-plane Ca mode relevant to the electron–phonon coupling. Our data analysis indicates that, below ~8 GPa, the softening contributes to the T c enhancement whilst, at higher pressures, it drives the system to a disordered phase presumably characterized by a disordering of the Ca sublattice. Thus, pressure induces a simultaneous order-disorder and lattice-softening phase transition from a good metal phase with high T c to a bad metal phase with low T c.
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References
Akrap, A., Berger, H., Forró, L., Tutiš, E., Sipos, B., and Kusmartseva, A.F., 2008, From Mott state to superconductivity in 1T-TaS2, Nature Mater. 7: 960.
Ashcroft, N.W., 1968, Metallic hydrogen: A high-temperature superconductor? Phys. Rev. Lett. 21: 1748.
Babaev, E., Sudbø, A., and Ashcroft N.W., 2005, Observability of a projected new state of matter: a metallic superfluid, Phys. Rev. Lett. 95: 105301.
Baroni, S., de Gironcoli, S., Dal Corso, A., and Giannozzi, P., 2001, Phonons and related crystal properties from density-functional perturbation theory. Rev. Mod. Phys. 73: 515.
Calandra, M., and Mauri, F. 2006, Possibility of superconductivity in graphite intercalated with alkaline earths investigated with density functional theory. Phys. Rev. B 74: 094507.
Calandra, M., and Mauri, F., 2005, Theoretical Explanation of Superconductivity in C6 Ca. Phys. Rev. Lett. 95: 237002.
Clarke, R., and Uher C., 1984, High pressure properties of graphite and its intercalation compounds, Adv. Phys. 33: 469–566.
Csànyi, G., Pickard, Ch.J., Simons B.D.., and Needs R.J., 2007, Graphite intercalation compounds under pressure: A first-principles density functional theory study, Phys. Rev. B 75: 085432.
Dresselhaus, M.S., and Dresselhaus G., 1981, Intercalation compounds of graphite, Adv. Phys. 30: 139–326.
Emery, N., Hérold C., and Lagrange Ph., 2005, Structural study and crystal chemistry of the first stage calcium graphite intercalation compound, J. Solid State Chem. 178: 2947–2952.
Emery, N., Hérold, C., D'Astuto, M., Garcia, V., Bellin, Ch., Marêché, J.F., Lagrange, P., Loupias, G., 2005, Superconductivity of Bulk CaC6, Phys. Rev. Lett. 95: 087003.
Fischer, J. E., and H. J. Kim, 1987, Pressure-induced staging transitions and stage disorder in dilute potassium-graphite intercalation compounds, Phys. Rev. B 35: 6826–6830.
Gao, L., Xue, Y.Y., Chen, F., Xiong, Q., Meng, R.L., Ramirez, D., Chu, C.W., Eggert, J.H., and Mao, H.K., 1994, Superconductivity up to 164 K in HgBa2 Ca m-1 Cu m O2m+2+δ (m=1, 2, and 3) under quasihydrostatic pressures, Phys. Rev. B 50: 4260–4263.
Gauzzi, A., Bendiab, N., D’Astuto, M., Canny, B., Calandra, M., Mauri, F., Loupias, G., Emety, N., Herold, C., Lagrange, P., Hanfland, M., and Mezouar, M., 2008, Maximum T c at the verge of a simultaneous order-disorder and lattice-softening transition in superconducting CaC6, Phys. Rev. B 78: 064506.
Gauzzi, A., Takashima, S., Takeshita, N., Terakura, C., Takagi, H., Emery, N., Hérold, C., Lagrange, P., and Loupias, G., 2007, Enhancement of superconductivity and evidence of structural instability in intercalated graphite CaC6 under high pressure, Phys. Rev. Lett. 98: 067002.
Grimvall, G., 1981, The Electron-Phonon Interaction in Metals, North-Holland, Amsterdam, 304 p.
Hannay, N.B., Geballe, T.H., Matthias, B.T., Andres, K., Schmidt, P., and MacNair, D., 1965, Superconductivity in Graphitic Compounds, Phys. Rev. Lett. 14: 225–226.
Jérome, D., 1990, Earlier and Recent Aspects of Superconductivity: Lectures from the international school, Erice, Trapani, Sicily, July 4–16, 1989. J.G. Bednorz, K.A. Müller (eds.), Springer-Verlag, Berlin, New York, 529 p.
Jishi, R.A., and Dresselhaus, M.S., 1992, Superconductivity in graphite intercalation compounds, Phys. Rev. B 45: 12465.
Kim, J.S., Boeri, L., Kremer, R.K., and Razavi, F.S., 2006, Effect of pressure on superconducting Ca-intercalated graphite CaC6, Phys. Rev. B 74: 214513.
Klein, C.A., Straub, W., and Diefendorf, R.J., 1962, Evidence of single-crystal characteristics in highly annealed pyrolytic graphite, Phys. Rev. 125: 468–470.
Lamura, G., Aurino, M., Cifariello, G., Gennaro Di, Andreone E.A., Emery, N., Hérold, C., Mareche, J.-F., and Lagrange, P, 2006, Experimental evidence of s-wave superconductivity in bulk CaC6, Phys. Rev. Lett. 96: 107008.
Little, W.A., 1964, Possibility of synthesizing an organic superconductor, Phys. Rev. 134: A1416–A1424.
Lortz, R., Wang, Y., Abe, S., Meingast, C., Paderno, Yu.B., Filippov, V., and Junod, A., 2005, Specific heat, magnetic susceptibility, resistivity and thermal expansion of the superconductor ZrB12, Phys. Rev. B 72: 024547.
Lüders, M., Marques, M.A.L., Lathiotakis, N.N., Floris, A., Profeta, G., Fast, L., Continenza, A., Massidda, S., and Gross, E.K.U., 2005, Ab initio theory of superconductivity. I. Density functional formalism and approximate functionals, Phys. Rev. B 72: 024545.
Li, Y., Zhang, L.-J., Cui, T., Liu, Y.-H., Ma, Y.-M., and Zou, G.-T., 2007, First-princiles prediction of high-pressure phase of CaC6, 2007, Chin. Phys. Lett. 24: 1668–1670.
Marques, M.A.L., Lüders, M., Lathiotakis, N.N., Profeta, G., Floris, A., Fast, L., Continenza, A., Gross, U., and Massidda, S., 2005, Ab initio theory of superconductivity. II. Application to elemental metals, Phys. Rev. B 72: 024546.
Mazin, I. I., 2005, Intercalant-driven superconductivity in YbC 6 and CaC 6, Phys. Rev. Lett. 95: 227001.
Mori, N., Takahashi, H., and Takeshita, N., 2004, Low-temperature and high-pressure apparatus developed at ISSP, University of Tokyo, High Press. Res. 24: 225–232.
Morosan, E., Zandbergen, H.W., Dennis, B.S., Bos, J.W.G., Onose, Y., Klimczuk, T., Ramirez, A.P., Ramirez, A.P., Ong, N.P., and Cava, R.J., 2006, Superconductivity in Cu x TiSe2, Nat. Phys. 2: 544–550.
Potter, M.E., Johnson, W.D., and Fischer, J.E., 1981, Transport properties of alkali metal-graphite intercalation compounds, Solid State Comm. 37: 713–718.
Primak, W., and Fuchs, L.H., 1954, Electrical conductivities of natural graphite crystals, Phys. Rev. 95: 22–30.
Profeta, G., Franchini, C., Lathiotakis, N.N., Floris, A., Sanna, A., Marques, M.A.L., Lüders, M., Massidda, S., Gross, E.K.U., and Continenza, A., 2006, Superconductivity in lithium, potassium, and aluminum under extreme pressure: a first-principles study. Phys. Rev. Lett. 96: 047003.
Rey, N., Toulemonde, P., Machon, D., Duclaux, L., Le Floch, S., Pischedda, V., Itié, J.P., Flank, A.-M., Lagarde, P., Crichton, W.A., Mezouar, M., Strässle, Th., Sheptyakov, D., Montagnac, G., San-Miguel, A., 2008, High-pressure behavior of CsC8 graphite intercalation compound: Lattice structures and phase-transition mechanism. Phys. Rev. B 77: 125433.
Shimizu, K., Ishikawa, H., Takao, D., Yagi, T., and Amaya, K., 2002, Superconductivity in compressed Li at 20 K, Nature 419: 597–599.
Shimizu, K., Kimura, T., Furomoto, S., Takeda, K., Kontani, K., Onuki, Y., and Amaya, K., 2001, Superconductivity in the nonmagnetic state of iron under pressure, Nature 412: 316–318.
Smith, R.P., Kusmartseva, A., Ko, Y.T.C., Saxena, S.S., Akrap, A., Forró, L., Laad, M., Weller, Th.E., Ellerby, M., and Skipper, N.T., 2006, Pressure dependence of the superconducting transition temperature in C6 Yb and C6 Ca. Phys. Rev. B 74: 024505.
Soule, D.E., 1958, Magnetic field dependence of the Hall Effect and magnetoresistance in graphite single crystals, Phys. Rev. 112: 698–707.
Weller, Th.E., Ellerby, M., Saxena, S.S., Smith, R.P., and Skipper, N.T., 2005, Superconductivity in the intercalated graphite compounds C6 Yb and C6 Ca, Nature Physics 1: 39–41.
Torikachvili, M.S., Bud’ko, S.L., Ni, N., and Canfield P.C., 2008, Pressure-induced superconductivity in CaFe2 As2, Phys. Rev. Lett. 101: 057006.
Chen, X.H., Wu, T., Wu, G., Liu, R.H., Chen, H., and Fang, D.F., 2008, Superconductivity at 43 K in SmFeAsO1−x F x , Nature. 453: 761–762.
Zhang, L., Xie, Y., Cui, T., Li, Y., He, Z., Ma, Y., and Zou, G., 2006, Pressure-induced enhancement of electron-phonon coupling in superconducting CaC6 from first principles, Phys. Rev. B 74: 184519.f
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Gauzzi, A. et al. (2010). High Pressure and Superconductivity: Intercalated Graphite Cac6 as a Model System. In: Boldyreva, E., Dera, P. (eds) High-Pressure Crystallography. NATO Science for Peace and Security Series B: Physics and Biophysics. Springer, Dordrecht. https://doi.org/10.1007/978-90-481-9258-8_33
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DOI: https://doi.org/10.1007/978-90-481-9258-8_33
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