Article

The interface magnetic energy in fcc Cu/Co/Cu(001) and Pd/Co/Pd(001) and the interlayer exchange coupling in bcc Fe/Cu/Fe(001) will be discussed and compared to recent theoretical models. The effect of interface magnetostriction and interface magnetic anisotropy will be described using a model proposed by Victora and MacClaren. The Victora-MacLaren theory of magnetic anisotropies is based on a generalized Néel pair interaction model that allows one to express the total interface energy in terms of the interface anisotropy and interface magnetoelastic contributions. It will be argued that the change in the sign of the interface anisotropy Ks as a result of replacing Cu atoms by Pd atoms is caused primarily by the enhanced role of the spin-orbit interaction in the Co-Pd pair interaction and in the tendency of Pd to acquire a significant magnetic moment in the proximity of ferromagnetic atoms. It will be shown that the interface lattice separations play an important role and the balance between these two magnetoelastic terms determines the total magnetoelastic contribution to the interface energy. The magnetoelastic interface contributions to Ks are +0.08 ergs/cm2 and +0.17 ergs/cm2 for the fcc Cu/Co/Cu(001) and Pd/Co/Pd(001) structures, respectively. The interlayer exchange coupling has been investigated in bcc trilayer structures Fe/Cu/XcCu1 - c/Cu/Fe where XcCu1 - c represents an alloyed atomic layer with X = Fe, Cr, Ag. The purpose of these studies was to determine the effect of foreign atoms inside a nonmagnetic spacer on the direct interlayer exchange coupling between the outside Fe layers mediated by the valence electrons of the Cu spacer. The experimental results will be compared with recent first principles calculations using the Layer Korringa-Kohn-Rostoker (LKKR) method. It will be shown that the local electron potential of the foreign atoms affects the spin transport across the spacer and is chiefly responsible for the observed behavior of the interlayer exchange coupling in Fe/Cu/XcCu1 - c/Cu/Fe. The interlayer e cxchange coupling depends very strongly on the magnetic state of the foreign atoms within the spacer. For foreign atoms with no long-range ferromagnetic order the exchange coupling is mainly affected by the 3d valence band electrons. Foreign atoms that are isoelectronic with the spacer atoms modify the strength of the exchange coupling only due to lattice relaxations that are associated with their atomic size.Key words: ultrathin metallic magnetic films, magnetic anisotropy, exchange interaction, Molecular Beam Epitaxy.

[Treatment of 3 patients with arrhythmias using "radiofrequency" ablation]

In 3 patients radiofrequency (RF) ablation of AV node (n = 2) and left sided accessory pathway (n = 1) was performed because of intractable tachyarrhythmias. RF ablation was made in the first patient (ablation of AV node) using 135 Watts during 72 sec., in the second patient (AV node ablation) 331 Watts during 185 sec., and in the last patient 883 Watts during 695 sec. In the last patient ablation of accessory pathway was unsuccessful and the patient has been successfully operated. AV conduction was interrupted in 2 cases. No complications were noted. General anesthesia was not required. All the patients were discharged in a good state.