Phonon density of states, anharmonicity, electron-phonon coupling and possible multigap superconductivity in the clathrate superconductors Ba8Si46 and Ba24Si100: Why is Tc different in these two compounds?

Rolf Lortz; Romain Viennois; Alexander Petrovic; Yuxing Wang; Pierre Toulemonde; Christoph Meingast; Michael Marek Koza; Hannu Mutka; Alexei Bossak; Alfonso San Miguel

doi:10.1103/physrevb.77.224507

arXiv · 0804.0535

Phonon density of states, anharmonicity, electron-phonon coupling and possible multigap superconductivity in the clathrate superconductors Ba8Si46 and Ba24Si100: Why is Tc different in these two compounds?

Rolf Lortz·Romain Viennois·Alexander Petrovic·Yuxing Wang·Pierre Toulemonde·Christoph Meingast·Michael Marek Koza·Hannu Mutka·Alexei Bossak·Alfonso San Miguel

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Abstract

We report a detailed study of specific heat, electrical resistivity and thermal expansion in combination with inelastic neutron and inelastic X-ray scattering to investigate the origin of superconductivity in the two silicon clathrate superconductors Ba8Si46 and Ba24Si100. Both compounds have a similar structure based on encaged barium atoms in oversized silicon cages. However, the transition temperatures are rather different: 8 K and 1.5 K respectively. By extracting the superconducting properties, phonon density of states, electron-phonon coupling function and phonon anharmonicity from these measurements we discuss the important factors governing Tc and explain the difference between the two compounds.

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Rolf Lortz, Romain Viennois, Alexander Petrovic, Yuxing Wang, Pierre Toulemonde, Christoph Meingast, Michael Marek Koza, Hannu Mutka, Alexei Bossak, Alfonso San Miguel. 2008-04-03. Phonon density of states, anharmonicity, electron-phonon coupling and possible multigap superconductivity in the clathrate superconductors Ba8Si46 and Ba24Si100: Why is Tc different in these two compounds?. https://doi.org/10.1103/physrevb.77.224507

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