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The study of spin-dependent single electron tunneling requires the preparation of particles with a nanometric size. These particles need not be ferromagnetic if the electrodes are. In order to fulfill the requirements of single electron tunneling effect, the preparation conditions of nanoparticles were studied, mainly for Fe and Au particles. The structure of these particles was then studied by scanning probe microscopy and transmission electron microscopy, and compared to the results of transport measurements. Particles with a diameter of the order of a nanometer were prepared and their lateral arrangement was controlled by self-organization phenomena. [ABSTRACT FROM AUTHOR]

Spin-dependent single electron tunneling was investigated in a magnetic double tunnel junction including Au nanoparticles as a center electrode. Tunnel magnetoresistance (TMR) clearly emerged with increasing spin-polarized current injected into Au nanoparticles and reached a maximum value of about 12% at 4.2 K. The observation indicates that spin accumulation occurs in Au nanoparticles and causes TMR. The spin relaxation time in Au nanoparticles, as estimated from the critical current for the appearance of TMR, is of the order of 10 ns, which is much longer than that in the bulk state. [ABSTRACT FROM AUTHOR]

Nanometric metallic particles were prepared on top of a thin epitaxial oxide layer. Samples with the following structure: Fe electrode/MgO/Fe particles were fabricated and the arrangement of the Fe particles could be tuned from random to self-aligned by simply varying the thickness of the Fe electrode. Under appropriate deposition conditions, the particles were found to be self-aligned along the <110> directions of the underlying Fe electrode. Scanning tunneling microscope (STM) showed that their mean diameter and size distribution were then significantly reduced compared to randomly organized particles. Transmission electron microscope (TEM) images indicated that the self-alignment process originates from the strain relaxation of the Fe electrode which favors faceting of its surface and the formation of pyramidal structures. These self-aligned particles may be straightly used for applications based on a thin oxide tunnel barrier such as single-electron tunneling devices. [ABSTRACT FROM AUTHOR]