318 research outputs found
Tunable spin-polaron state in a singly clamped semiconducting carbon nanotube
We consider a semiconducting carbon nanotube (CNT) laying on a ferromagnetic
insulating sub-strate with one end depassing the substrate and suspended over a
metallic gate. We assume that the polarised substrate induces an exchange
interaction acting as a local magnetic field for the electrons in the
non-suspended CNT side. Generalizing the approach of I. Snyman and Yu.V.
Nazarov [Phys. Rev. Lett. 108, 076805 (2012)] we show that one can generate
electrostatically a tun-able spin-polarized polaronic state localized at the
bending end of the CNT. We argue that at low temperatures manipulation and
detection of the localised quantum spin state is possible
Spin Gating of Mesoscopic Devices
Inefficient screening of electric fields in nanoconductors makes electric
manipulation of electronic transport in nanodevices possible. Accordingly,
electrostatic (charge) gating is routinely used to affect and control the
Coulomb electrostatics and quantum interference in modern nanodevices. Besides
their charge, another (quantum mechanical) property of electrons - their spin -
is at the heart of modern spintronics, a term implying that a number of
magnetic and electrical properties of small systems are simultaneously
harvested for device applications. In this review the possibility to achieve
"spin gating" of mesoscopic devices, i.e. the possibility of an external spin
control of the electronic properties of nanodevices is discussed. Rather than
the Coulomb interaction, which is responsible for electric-charge gating, we
consider two other mechanisms for spin gating. These are on the one hand the
magnetic exchange interaction in magnetic devices and on the other hand the
spin-orbit coupling ("Rashba effect"), which is prominent in low dimensional
conductors. A number of different phenomena demonstrating the spin gating
phenomenon will be discussed, including the spintro-mechanics of magnetic
shuttling, Rashba spin splitting, and spin-gated weak superconductivity.Comment: Submitted to a special issue of "Synthetic Metals" to appear in March
201
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
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 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 . 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
Spintromechanics of a Magnetic Nanoshuttle
We investigate theoretically the prospects for using a magnetic
nanoelectromechanical single-electron tunneling (NEM-SET) device as an
electronic spin filter. We find that strong magnetic exchange forces on the net
spin of the mobile central dot of the NEM-SET structure lead to spin-dependent
mechanical displacements ("spin polarons"), which give rise to vastly different
tunnelling probabilities for electrons of different spin. The resulting spin
polarization of the current can be controlled by bias and gate voltages and be
very close to 100% at voltages and temperatures below a characteristic
correlation energy set by the sum of the polaronic and Coulomb blockade
energies.Comment: Accepted for publication as a Rapid Communication in Phys. Rev. B and
selected as an "Editors' Suggestion" paper. This version has minor
modifications compared to arXiv:1205.2979, which it replace
Photo-spintronics of spin-orbit active electric weak links
We show that a carbon nanotube can serve as a functional electric weak link
performing photo-spintronic transduction. A spin current, facilitated by strong
spin-orbit interactions in the nanotube and not accompanied by a charge
current, is induced in a device containing the nanotube weak link by circularly
polarized microwaves. Nanomechanical tuning of the photo-spintronic
transduction can be achieved due to the sensitivity of the spin-orbit
interaction to geometrical deformations of the weak link.Comment: 4 pages, 3 figure
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