Theoretical investigation of the magnetic behavior of substitutional Fe impurities in Zn, Cd, and Al hosts

Abstract

Calculations for substitutional Fe in Al in the absence of lattice relaxation yield a large value for the magnetic moment at the impurity site. The lack of magnetic response observed experimentally has been attributed to the presence of spin fluctuations. However, more recent calculations show that the moment at the Fe impurity could vanish in the presence of lattice relaxation around the impurity, thus rendering unnecessary a description in terms of spin fluctuations. We have performed electronic-structure calculations to investigate the magnetic behavior of substitutional Fe impurities in Zn, Cd, and Al hosts as a function of lattice relaxation. In the case of Fe in Al, the theoretical results are sensitive to the lattice constant used for fcc Al. If the experimental value is used, the Fe moment decreases drastically but does not vanish at the experimentally observed relaxation values. In the case of Zn and Cd hosts, the calculated moment remains quite large for all reasonable values of relaxation. Our results indicate that a description in terms of spin fluctuations and high values of the Kondo temperature should be used for Fe in Zn and Cd and may also be appropriate to describe Fe impurities in Al.