Effect of bidimensional Fe clusters on magnetic properties of Fe/Cr superlattices

The effect of bidimensional Fe clusters and intermixing between the Fe and Cr atoms on the magnetic properties of Fe/Cr superlattices is studied in the framework of collinear and noncollinear periodic Anderson model. Self-consistent calculations performed for the superlattices with Fe layers thicknesses equivalent to 3 and 7 Å demonstrate the dependence of the magnetic moments distribution not only on the thickness of Fe layers but on the compositional structure of the interlayers due to different Cr surroundings of the Fe atoms. The superlattices with continuously smooth Fe layers of both thicknesses result in a collinear orientation of Fe and Cr atomic moments. The onset of the Fe clusters and switching on the intermixing of the atoms by a stochastic procedure do not destabilize the collinear orientation for the superlattices with Fe thickness equivalent to 7 Å. On the contrary, the superlattices with Fe thickness equivalent to 3 Å results in noncollinear orientation of the magnetic moments for the intermixed continuous Fe layers as much as for the Fe clusters in the interlayers before and after intermixing. The clusters are shown have an arbitrary orientation of the average magnetic moments, so that the structure is considered to be a superparamagnetic system.