Volume 96, Issue 7, 01 October 2004
Index of content:
- MAGNETISM AND SUPERCONDUCTIVITY (PACS 74-76)
Peculiar magnetic and electrical properties near structural percolation in metal-insulator granular layers96(2004); http://dx.doi.org/10.1063/1.1786651View Description Hide Description
We study multilayers, varying from granular to continuous structure with CoFe nominal thickness . Structural percolation takes place at , changing from activated to metallic conductance. A sharp anomaly in ac coercivity of magneto-optical Kerr effect and in magnetization by superconducting quantum interferometer device is found at , interpreted as transition from superferromagnetism (by dipolar coupled CoFe clusters) to exchange ferromagnetism. Onset at of anisotropic magnetoresistance (AMR) is attributed to skew scattering of bandlike electrons within giant fractal clusters. These structures may cause the observed Barkhausen noises in and AMR at , disappearing at .
96(2004); http://dx.doi.org/10.1063/1.1771474View Description Hide Description
The origin of anomalous negative magnetoresistance and its temperature dependence in polycrystalline films prepared by pulse laser deposition was studied. The investigation of structural, transports, magnetic, and ferromagnetic resonance properties of the films suggests contributions of different mechanisms in magnetotransport. At low magnetic fields the main contribution to magnetoresistance is due to the transport between the areas with different orientation of magnetic moments, while at high fields it is an electron scattering of in spin-disordered areas.