Abstract
We present first-principles charge- and spin-self-consistent electronic structure computations on the Heusler-type disordered alloys for three different metalloids and Al). In these calculations we use the methodology based on the Korringa-Kohn-Rostoker formalism and the coherent-potential approximation generalized to treat disorder in multicomponent complex alloys. Exchange correlation effects are incorporated within the local spin density approximation. Total energy calculations for show that V substitutes preferentially on the site, not on the site, in agreement with experiment. Furthermore, calculations have been carried out for alloys (with and together with the end compounds and and the limiting cases of a single V impurity in and a single impurity in We delineate clearly how the electronic states and magnetic moments at various sites in evolve as a function of the V content and the metalloid valence. Notably, the spectrum of and Ga) develops a pseudogap for the majority as well as minority spin states around the Fermi energy in the V-rich regime, which, together with local moments of impurities, may play a role in the anomalous behavior of the transport properties. The total magnetic moment in is found to decrease nonlinearly, and the moment to increase with increasing x; this is in contrast to expectations of the “local environment” model, which holds that the total moment should vary linearly while the moment should remain constant. The common-band model, which describes the formation of bonding and antibonding states with different weights on the different atoms, however, provides insight into the electronic structure of this class of compounds.
- Received 22 July 1999
DOI:https://doi.org/10.1103/PhysRevB.60.13396
©1999 American Physical Society