Electronic structure and magnetic properties ofNi3nAlnclusters

Abstract

The equilibrium structure, electronic, and magnetic properties of ${\text{Ni}}_{3n}{\text{Al}}_{n}$, $(n=1,\text{ }8)$ clusters are investigated using ab initio total-energy calculations based on density functional theory. Asymmetric and amorphous structures are observed for $ng1$ clusters, in contrast with the earlier work reported based on Gupta potentials; where, clusters with ${\text{Ni}}_{3}\text{Al}$ compositions were found to be symmetric. Magnetic moment per atom in these clusters is significantly enhanced with respect to the bulk. The distribution of magnetic charge on Ni and Al atoms is highly inhomogeneous and depends on their number of Al and Ni neighbors. The Al atoms quench the magnetic moments of ${\text{Ni}}_{3n}{\text{Al}}_{n}$ clusters when compared with the magnetic moments of pure Ni clusters. The analysis of the charge density shows a net transfer of charge from $s$-type orbital of Ni to $p$-type orbital of Al. The density of states exhibits features like Heusler alloys. The implications of this on the conductance in such clusters are discussed.