Electronic Topological Transitions and Compositional Order in CuPd and CuPt Alloys

Abstract

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 ETT1). As it is well known1 the ETT’s influence transport properties, elastic properties and electron-phonon interaction2. Moreover, as we have recently shown, they affect the crystal equilibrium volumes3. 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 different5. 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 KrivoglazClapp-Moss6 model (KCM) will prove useful.