22,382 research outputs found
Distortion and electric field control of band structure of silicene
Density functional theory with local density approximation for exchange and
correlation functional is used to tune the electronic band structure of
silicene monolayer. The cohesive energy of free standing monolayer is
increasing (decreasing) with external electric field (distortion). Electrons in
silicene behave like Dirac fermions, when the bond angle between the Si atoms
is larger than . Large distortions destroy the electronic
structure of silicene and silicene is no longer a semi-metallic material, and
the distorted silicene acts like an -doped system. Electric field opens a
band gap around point in the Brillouin zone, which increases with electric
field. The bond angle between the Si atoms is a key player to determine the
presence or absence of Dirac cones in silicene.Comment: Europhysics Lett. Accepted (2014
A Calculus of Mobility and Communication for Ubiquitous Computing
We propose a Calculus of Mobility and Communication (CMC) for the modelling
of mobility, communication and context-awareness in the setting of ubiquitous
computing. CMC is an ambient calculus with the in and out capabilities of
Cardelli and Gordon's Mobile Ambients. The calculus has a new form of global
communication similar to that in Milner's CCS. In CMC an ambient is tagged with
a set of ports that agents executing inside the ambient are allowed to
communicate on. It also has a new context-awareness feature that allows
ambients to query their location. We present reduction semantics and labelled
transition system semantics of CMC and prove that the semantics coincide. A new
notion of behavioural equivalence is given by defining capability barbed
bisimulation and congruence which is proved to coincide with barbed
bisimulation congruence. The expressiveness of the calculus is illustrated by
two case studies.Comment: In Proceedings WWV 2015, arXiv:1508.0338
On-Chip Photonic Transistor based on the Spike Synchronization in Circuit QED
We consider the single photon transistor in coupled cavity system of
resonators interacting with multilevel superconducting artificial atom
simultaneously. Effective single mode transformation is used for the
diagonalization of the the hamiltonian and impedance matching in terms of the
normal modes. Storage and transmission of the incident field are described by
the interactions between the cavities controlling the atomic transitions of
lowest lying states. Rabi splitting of vacuum induced multiphoton transitions
is considered in input/output relations by the quadrature operators in the
absence of the input field. Second order coherence functions are employed to
investigate the photon blockade and localization-delocalization transitions of
cavity fields in oscillating regime of photon states described by the the
population imbalance. Refection and transmission of cavity output fields are
investigated in the presence of the multilevel transitions. Accumulation and
firing of the reflected and transmitted fields are used to investigate the
synchronization of the bunching spike train of transmitted field and population
imbalance of cavity fields. In the presence of single photon gate field, gain
enhancement is explained for transmitted regime.Comment: 8 pages,10 figure
Strain-induced half-metallic ferromagnetism in zinc blende CrP/MnP superlattice: First-principles study
Using first-principles calculations within generalized gradient
approximation, the electronic and magnetic properties of zinc blende (zb)
CrP/MnP superlattice are investigated. The equilibrium lattice constant is
calculated to be \AA. The stability of ferromagnetic zb CrP/MnP
superlattice against antiferromagnetism is considered and it is found that the
ferromagnetic CrP/MnP superlattice is more stable than the antiferromagnetic
one. It is shown that at the equilibrium lattice constant the CrP/MnP
superlattice does not show any half metallicity mainly due to the minority
states of Cr and Mn. However, if strain is imposed on the CrP/MnP
superlattice then the minority electrons shift to higher energies and
the proposed superlattice becomes a half-metal ferromagnet. The effect of
tetragonal and orthorhombic distortions on the half metallicity of zb CrP/MnP
superlattice is also discussed. It is also shown that InP-CrP/MnP/InP is a true
half-metal ferromagnet. The half metallicity and magnetization of these
superlattices are robust against tetragonal/ orthorhombic deformation.Comment: 5 pages, 4 figure
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