Manipulating the Magnetic Moment of Palladium Clusters by Adsorption and Dissociation of Molecular Hydrogen

Abstract

There is a sizable probability for the dissociation of H2 deposited at low energy on palladium clusters supported on graphene. This is accompanied by a total or partial quenching of the magnetic moment of the cluster, and we have investigated the interplay between these two processes: magnetization change and molecular dissociation. For this purpose, the density functional formalism has been used, in the form of ab initio molecular dynamics simulations and static calculations. Two different cluster sizes have been investigated, Pd6 and Pd13, and the conclusion is that the size of the Pd cluster has a strong influence on the sequence of these two processes. The effect of H2 dissociation is to reduce the magnetic moments of both clusters by about 2 μB, resulting in unpolarized Pd6 on the one hand and Pd13 with a magnetic moment of 2 μB on the other. In the case of Pd6, the quenching of the magnetic moment occurs immediately after the dissociation of the H2 molecule. In contrast, the quenching of the magneti...