First-principles investigations of multimetallic transition metal clusters

Abstract

This brief overview summarizes the state-of-the-art of simulations of transition metal nanoclusters based on density functional theory calculations. Besides the monometallic clusters like iron, we focus on alloy nanoclusters like Fe-Pt, Co-Pt and (Ni, Co)-Mn-Ga which are of current interest for recording media and actuators involving the magnetic shape memory effect, respectively. Although catalysis is not the subject of the present paper, trimetallic nanoclusters are of special interest because the third element can be used to achieve higher catalytic and selective properties compared to the corresponding monometallic and bimetallic clusters. For clusters of Fe-Pt and Co-Pt below a critical size, the L1₂ structure with its technologically relevant high magnetocrystalline anisotropy, is difficult to stabilize. For trimetallic systems like Ni-Mn-Ga, the rather versatile properties of the bulk material can be used to achieve shape changes or magnetocaloric effects (depending on the composition) also in nanoclusters. More importantly, it might be cheaper to manufacture the nanocrystalline materials from the trimetallic nanoclusters than to fabricate corresponding single-crystal bulk systems.

Keywords:

• ab-initio
• clusters
• transition metals

Acknowledgements

One of us (PE) would like to thank Peter Weinberger for the hospitality and the extremely nice workshop held in Cocoyoc, Mexico, in February 2008. Financial support was granted by the Deutsche Forschungsgemeinschaft (SFB 445 and SPP 1239). We thank the staff of the John von Neumann Institute for Computing for substantial support of our project Nanometer-scale ab-initio investigations of functional magnetic materials.