Electronic topological transitions and compositional order in CuPd and CuPt alloys

摘要

Varying the electron per atom ratio in random noble-transition metal alloys not only changes their Fermi volumes but also causes transitions in their Fermi Surface (FS) topologies (Electronic Topological Transitions or ETT~1). As it is well known~1 the ETT's influence transport properties, elastic properties and electron-phonon interaction~2. Moreover, as we have recently shown, they affect the crystal equilibrium volumes~3. In this communication, we present a first principle comparative study, based on the relativistic Korringa Kohn Rostoker Coherent Potential Approximation (KKR-CPA)~4, of CuPt and CuPd random alloys. These systems have a peculiar interest since, although isoelectronic, their phase diagrams are profoundly different~5. In this paper, we attempt to trace the seeds of the low temperature phase equilibria of these alloys in the FS's of their homogeneous solid solution phases. In our analysis both the ETT theory and the Krivoglaz-Clapp-Moss~6 model (KCM) will prove useful.