Magnetic states of Fe/Cr multilayer structures with ultrathin iron layers
A.B. Drovosekov, N.M. Kreines, and D.I. Kholin
P.L. Kapitza Institute for Physical Problems, 2 Kosygina Str., Moscow 119334, Russia
Received February 12, 2010
The evolution of magnetic properties was studied in Fe/Cr superlattices with nominal iron layer thickness diminishing down to atomic values, where these layers were no longer continuous. The investigations were performed using multilayer structures with Fe thickness of
2–6 Å for chromium spacers 10 Å and 20 Å thick. The samples were prepared by the molecular beam epitaxy technique. The measurements of static magnetization, complex magnetic susceptibility and FMR spectra were
carried out. It is found that there may occur different magnetic phases in the system depending on nominal Fe layer thickness and temperature: superparamagnetic phase, the magnetically ordered one, and non-ergodic state with sample magnetic history-dependent magnetization. The observed non-ergodic phase is shown to exhibit spin glass properties. A qualitative phase diagram of the system magnetic states is constructed.
PACS: 75.50.Lk Spin glasses and other random magnets; PACS: 75.50.Tt Fine-particle systems; nanocrystalline materials; PACS: 75.70.Cu Magnetic properties of interfaces (multilayers, superlattices, heterostructures).