Crossover Antiferro-Superparamagnetism and Related Kondo-Like Anomalies of Resistivity in Clustered Fe/Cr Multilayers

The magnetic and magnetoresistive properties of nanostructured Fe/Cr multilayers with ultra-thin Fe layers (the nominal Fe thickness tFe is down to 0.3 A) have been investigated at low temperatures (down to 2 K) in magnetic fields up to 90 kOe. Nanostructures were MBE grown in ultrahigh vacuum on single crystal MgO substrates. It is shown that Fe layers in nanostructures with tFe