Interaction effects in dilute cluster-assembled magnetic nanostructures

Abstract

We have prepared dilute nanostructured magnetic samples by codeposition of preformed cobalt clusters with a narrow size distribution around 40 atoms per cluster in silver matrices. Magnetoresistance measurements are used to derive information about the magnetic structure of the samples. Effects of cluster size distribution or anisotropy can be neglected in our samples. Deviations from simple Langevin-type magnetization are observed as a function of temperature and identified as due to intercluster interactions. Pairwise magnetostatic and indirect exchange interactions as well as the model of interacting superparamagnets are found to be not adequate to explain the observed temperature dependences. We propose an interpretation of a correlated spin glass, which shows that for small clusters, spin glass behavior can be observed even at high dilutions.

Interactions controlled evolution of complex magnetoresistance in as-deposited Ag100−Co nanogranular films with perpendicular magnetic anisotropy

“…These films are studied extensively owing to scientific and technological challenges involved [2][3][4][5]. However, due to the complexity of their microstructure, many of the physical properties of these granular films are yet to be clearly understood.…”

Surface scattering dominated magnetotransport for improved quantitative estimation of particle size in Ag100−xCox nanogranular films

“…In the ongoing miniaturization of magnetic data storage media, the superamaganetic (SPM) limit, as well as interparticle interactions become critical and limiting issues [2]. So, developing an elaborated understanding of the magnetic properties, especially the interparticle interactions are crucial to fully exploit such systems in the development of high performance magnetic materials and spin-dependent electronic devices [3].…”

Perpendicular magnetic anisotropy and complex magnetotransport behavior of cobalt nanoparticles in silver matrix

“…[3][4][5][6] One of the main challenges of data storage devices is the miniaturization of magnetic data bits to nanometric size while still keeping them thermally stable. 7,8 The major factor limiting the possibility of using these structures is the so-called superparamagnetic (SPM) limit that decreases the storage time of written information and requires the production of particles with a large anisotropy. 9 In such desired systems, high ferromagnetic (FM) content could sometimes lead to magnetic domains with anisotropy axis oriented normal to the film plane.…”