8:00 AM–10:24 AM, Monday, March 13, 2006
Baltimore Convention Center - 342
Sponsoring Unit:
DMP
Chair: Lance Cooley, Brookhaven National Laboratory
Abstract ID: BAPS.2006.MAR.A39.11
10:00 AM–10:12 AM
Giovanni B. Bachelet
(INFM and Dipartimento di Fisica, Universit\`a ``La Sapienza'', I-00185 Roma, Italy)
Lilia Boeri
(Max-Planck-Institut f\"{u}r Festk\"{o}rperforschung, D-70569 Stuttgart, Germany)
Matteo Giantomassi
(UPCPM, Universit\'e Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium)
We report a first-principles study of structural, electronic and vibrational properties of the superconducting C$_{32}$ phase of the ternary alloy CaAl$_{2-x}$Si$_x$, both in the experimental range of stability, $0.6 \leq x \leq 1.2$, and outside, in the limits of high Al and high Si concentration. We find that the dependence of the electronic bands on composition is well described by a rigid-band model, which breaks down outside the experimental range of stability. This breakdown, in the limit of high Al concentration, is connected to vibrational instabilities, and results in important differences between CaAl$_2$ and MgB$_2$. Unlike MgB$_2$, the interlayer band and the out-of-plane phonons play a major role on the stability and superconductivity of CaAlSi and related C$_{32}$ intermetallics.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2006.MAR.A39.11