D=6 massive spinning particle

The massive spinning particle in six-dimensional Minkowski space is described as a mechanical system with the configuration space ${\ R}% ^{5,1}\times {\ CP}^3$. The action functional of the model is unambigiously determined by the requirement of identical (off-shell) conservation for the phase-space counterparts of three Casimir operators of Poincar\'e group. The model is shown to be exactly solvable. Canonical quantization of the model leads to the equations on wave functions which prove to be equivalent to the relativistic wave equations for the irreducible$6d$ fields.Comment: 8 pages, LaTe

Giant conductance oscillations in a normal mesoscopic ring induced by an SNS Josephson current

A theoretical explanation of giant conductance oscillations observed in normal mesoscopic rings with superconducting ``mirrors" is proposed. The effect is due to resonant tuning of Andreev levels to the Fermi level, which enhances the transparency of the system to the normal current. The mechanism is demonstrated for a one-dimensional model system.Comment: 10 pages, RevTeX, 3 fig. available upon request, Appl. Phys. Report 94-

Nanomechanics of a magnetic shuttle device

We show that self sustained mechanical vibrations in a model magnetic shuttle device can be driven by both the charge and the spin accumulated on the movable central island of the device. Different scenarios for how spin- and charge-induced shuttle instabilities may develop are discussed and shown to depend on whether there is a Coulomb blockade of tunneling or not. The crucial role of electronic spin flips in a magnetically driven shuttle is established and shown to cause giant magnetoresistance and dynamic magnetostriction effects