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We studied the influence of the superconducting state on the magnetic properties in a thick IrMn(100 nm)/NiFe(100 nm) bilayer deposited by magnetron sputtering onto an yttrium–barium–copper–oxide (YBCO) substrate that was previously synthesized by the acetate method. The results from magnetization experiments showed that the sign of the effective exchange fields switched from positive, in the as-prepared heterostructure, to negative values when the sample goes below the superconducting temperature of the YBCO substrate. We, thus, demonstrated that the YBCO substrate, in its superconducting state, strongly influences the magnetic anisotropy of the thick ferromagnetic NiFe layer due to the proximity effect that occurs at the YBCO–NiFe interface, where a non-collinear magnetic spin structure is formed during the in-field sample deposition.

Mossbauer spectroscopy, in a broad temperature interval of 12–425 K, has been applied to investigate the spin reorientation dynamics caused by the temperature induced magnetoelastic effect on Al(x μm)/Metglas 2605S2 (20 μm)/Al(x μm) trilayers (x=0; 2.5; 5 and 20). It was found that the angle between the average sample magnetization and gamma ray direction (perpendicular to the sample plane) depends on the Al layer thickness. For temperatures smaller than 260 K, saturation of spin reorientation, which can be controlled by adjusting the Al thickness, was reached for Al thicknesses larger than and equal to 5 μm. For a 20 μm Al thickness, changes in the F57e atom spin and charge densities have also been observed. A simple spin model has been proposed to describe qualitatively the spin reorientation effect as well as the influence of the Al thickness on the spin reorientation sensitivity.

We have studied the influence of an inserted nano-oxide layer (NOL) on the interfacial magnetism in spin-valve systems showing the giant magnetoresistance effect. Specifically, we performed a magnetic depth profile of these structures with and without a NOL, using the x-ray magnetic circular dichroism technique. We found that insertion of a NOL into the spin-valve structure is correlated with a stronger reduction of the magnetic moments at the ferromagnetic (FM)∕NOL∕FM interface in comparison with a spin valve without NOL.

Spin glass-like behavior has been recently observed in a ceramic Zn0.5Co0.9Fe1.2Ti0.4O4 spinel oxide.1 This motivated our interest to study how the spin glass-like behavior of magnetic clusters in a diamagnetic matrix correlates to that of nonmagnetic or weakly magnetic clusters in a ferromagnetic matrix, Mossbauer effect, ac susceptibility, field cooled and zero field cooled magnetization, hysteresis loops, and γ–γ perturbed angular correlation (PAC) have been measured for TM0.5−xCo0.9Fe1.2+xTi0.4O4 (x=0.0 and 0.2) spinel oxide with TM=Zn and Cu. The variation of coercive field with temperature has been found to fit a double exponential function form Hc(T)=H1e−β1T+H2e−β2T where Hi and βi are constants for the sample with x=0.0 and TM=Zn. The exponential increase in coercive field can be linked to increased effective clusters arising from ions occupying A and B sites with Fe on both sites. This is in agreement with the Mossbauer measurements which show superparamagnetic fluctuations. The ac susceptibility...