Superconductivity and physical properties of Ba24Si100 determined from electric transport, specific-heat capacity, and magnetic susceptibility measurements

Both ${\mathrm{Ba}}_{24}{\mathrm{Si}}_{100}$ and ${\mathrm{Ba}}_{24}{\mathrm{Ge}}_{100}$ with crystallographically identical structure are found to be superconducting at 1.4 and 0.27 K, respectively. Physical properties of this superconductor ${\mathrm{Ba}}_{24}{\mathrm{Si}}_{100}$ are studied by electric transport, specific heat capacity, and magnetic susceptibility measurements. The density of states at the Fermi level ${N}_{{E}_{F}}=0.148$ states ${\mathrm{eV}}^{\ensuremath{-}1}\phantom{\rule{0.3em}{0ex}}{(\mathrm{Si}\phantom{\rule{0.3em}{0ex}}\text{atom})}^{\ensuremath{-}1}$ and a distinct jump of ${C}_{p}$ at the superconducting transition temperature $\ensuremath{\Delta}{C}_{p}=0.272\phantom{\rule{0.3em}{0ex}}\mathrm{J}\phantom{\rule{0.2em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}\phantom{\rule{0.2em}{0ex}}{\mathrm{mol}}^{\ensuremath{-}1}$ are obtained. An exponential fit of ${C}_{p}$ below the superconducting states gives an energy gap $2\ensuremath{\Delta}=0.423\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ and shows that this is a superconductor having $s$-wave character or isotropic energy gap. On the basis of our experimental data other important physical parameters are also derived.