Role of tetrahedrally coordinated dopants in palladium hydrides on their superconductivity and inverse isotope effect
Sprache des Titels:
Absorption of hydrogen by palladium causes PdH to become superconducting below Tc ~ 9 K. Due to the presence of one octapore and two tetrapores per each Pd atom, it is
believed that Tc of PdHx>1 should increase further. Here, using ab initio calculation we show that (i) H placed in tetrapores of PdH x induces a wide optical gap in the phonon density of states, which significantly reduces the electron?phonon coupling, and that (ii) the energetically
preferable octapores filled by H enable the 9 K superconductivity only. This scenario may close a long-standing problem of the high-Tc palladium hydrides. Moreover, simulating the pore population by H and D, within ab initio molecular dynamics, we are able to explain the inverse isotope effect in the framework of the Bardeen?Cooper?Schrieffer theory.