2,763 research outputs found
Exchange interaction and Fano resonances in diatomic molecular systems
We propose a mechanism to use scanning tunneling microscopy (STM) for direct
measurements of the two-electron singlet-triplet exchange splitting in
diatomic molecular systems, unsing the coupling between the molecule and the
substrate electrons. The different pathways for electrons lead to interference
effects and generate kinks in the differential conductance at the energies for
the singlet and triplet states. These features are related to Fano resonance
due to the branched electron wave functions. The ratio between the tunneling
amplitudes through the two atoms can be modulated by spatial movements of the
tip along the surface.Comment: 4 pages, 2 figures, submitted - Changes in Fig. 1 (panel c) added),
and minor modification in the main text - new version, as publishe
Detection of exchange interaction in STM measurements through Fanolike interference effects
We address Fano-like interference effects in scanning tunneling microscopy
(STM) measurements of nanoscale systems, e.g. two-level systems. Common for
these systems is that second order tunneling contributions give rise to
interference effects that cause suppressed transmission through the system for
certain energies. The suppressed transmission is measurable either in the
differential conductance or in the bias voltage derivative thereof.Comment: 9 pages, 3 figures, submitted: in addition to the results published
in Phys. Rev. B, 75, 153309 (2007), this paper contains a more thorough
discussion on the used transport formalism, studies of asymmetric couplings
to the substrate, and discussion of non-resonant levels. The non-resonant
case is related to spin-dependent tunnelin
Vibrating Superconducting Island in a Josephson Junction
We consider a combined nanomechanical-supercondcuting device that allows the
Cooper pair tunneling to interfere with the mechanical motion of the middle
superconducting island. Coupling of mechanical oscillations of a
superconducting island between two superconducting leads to the electronic
tunneling generate a supercurrent which is modulated by the oscillatory motion
of the island. This coupling produces alternating finite and vanishing
supercurrent as function of the superconducting phases. Current peaks are
sensitive to the superconducting phase shifts relative to each other. The
proposed device may be used to study the nanoelectromechanical coupling in case
of superconducting electronics.Comment: 4 pages, 3 figures, to appear in Phys. Rev. Let
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