Pairs of 3d impurities in Au:: local moments and exchange coupling from first-principles

We use a first-principles approach, implemented directly in real space, to obtain the electronic structure and magnetic behavior of a pair of adjacent 3d impurities, one of them Fe, in Au. We find that the inter-atomic exchange coupling J between the Fe and the 3d impurity in the pair is negative for Ti, V and Cr leading to an antiferromagnetic arrangement, while in all other cases J is positive and a ferromagnetic configuration is favored. The local moment of Fe is not significantly affected by the presence of the 3d neighbors. Therefore, the strongly modified values of hyperfine field observed in some of these systems cannot be explained by changes in the moment of the Fe probe. (C) 2001 Elsevier Science B.V. All rights reserved.