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

Superconductive pumping of nanomechanical vibrations

We demonstrate that a supercurrent can pump energy from a battery that provides a voltage bias into nanomechanical vibrations. Using a device containing a nanowire Josephson weak link as an example we show that a nonlinear coupling between the supercurrent and a static external magnetic field leads to a Lorentz force that excites bending vibrations of the wire at resonance conditions. We also demonstrate the possibility to achieve more than one regime of stationary nonlinear vibrations and how to detect them via the associated dc Josephson currents and we discuss possible applications of such a multistable nanoelectromechanical dynamics.Comment: 4 pages, 5 figure

Umklapp-Assisted Electron Transport Oscillations in Metal Superlattices

We consider a superlattice of parallel metal tunnel junctions with a spatially non-homogeneous probability for electrons to tunnel. In such structures tunneling can be accompanied by electron scattering that conserves energy but not momentum. In the special case of a tunneling probability that varies periodically with period $a$ in the longitudinal direction, i.e., perpendicular to the junctions, electron tunneling is accompanied by "umklapp" scattering, where the longitudinal momentum changes by a multiple of $h/a$. We predict that as a result a sequence of metal-insulator transitions can be induced by an external electric- or magnetic field as the field strength is increased.Comment: 5 pages, 3 figure

Vibrational Instability due to Coherent Tunneling of Electrons

Effects of a coupling between the mechanical vibrations of a quantum dot placed between the two leads of a single electron transistor and coherent tunneling of electrons through a single level in the dot has been studied. We have found that for bias voltages exceeding a certain critical value a dynamical instability occurs and mechanical vibrations of the dot develop into a stable limit cycle. The current-voltage characteristics for such a transistor were calculated and they seem to be in a reasonably good agreement with recent experimental results for the single $C_{60}$-molecule transistor by Park et al.(Nature {\bf 407,} (2000) 57).Comment: 5 pages, 3 figure

Suppression of stochastic fluctuations of suspended nanowires by temperature-induced single-electron tunnelling

We investigate theoretically the electromechanical properties of freely suspended nanowires that are in tunnelling contact with the tip of a scanning tunnelling microscope (STM) and two supporting metallic leads. The aim of our analysis is to characterize the fluctuations of the dynamical variables of the nanowire when a temperature drop is mantained between the STM tip and the leads, which are all assumed to be electrically grounded. By solving a quantum master equation that describes the coupled dynamics of electronic and mechanical degrees of freedom we find that the stationary state of the mechanical oscillator has a Gaussian character, but that the amplitude of its root-mean square center-of-mass fluctuations is smaller than would be expected if the system were coupled only to the leads at thermal equilibrium.Comment: Published versio

Resonant microwave properties of a voltage-biased single-Cooper-pair transistor

We consider the microwave dynamics and transport properties of a voltage-biased single-Cooper-pair transistor. The dynamics is shown to be strongly affected by interference between multiple microwave-induced inter-level transitions. As a result the magnitude and direction of the dc Josephson current are extremely sensitive to small variations of the bias voltage and to changes in the frequency of the microwave field.Comment: 6 pages, 4 figure

Electronic spin working mechanically

A single-electron tunneling (SET) device with a nanoscale central island that can move with respect to the bulk source- and drain electrodes allows for a nanoelectromechanical (NEM) coupling between the electrical current through the device and mechanical vibrations of the island. Although an electromechanical "shuttle" instability and the associated phenomenon of single-electron shuttling were predicted more than 15 years ago, both theoretical and experimental studies of NEM-SET structures are still carried out. New functionalities based on quantum coherence, Coulomb correlations and coherent electron-spin dynamics are of particular current interest. In this article we present a short review of recent activities in this area.Comment: 17 pages, 11 figures. arXiv admin note: substantial text overlap with arXiv:1303.074