5,772 research outputs found
Impurity scattering in a d-wave superconductor
The influence of (non-magnetic and magnetic) impurities on the transition
temperature of a d-wave superconductor is studied anew within the framework of
BCS theory. Pairing interaction decreases linearly with the impurity
concentration. Accordingly suppression is proportional to the
(potential or exchange) scattering rate, , due to impurities. The
initial slope versus is found to depend on the superconductor contrary
to Abrikosov-Gor'kov type theory. Near the critical impurity concentration
drops abruptly to zero. Because the potential scattering rate is
generally much larger than the exchange scattering rate, magnetic impurities
will also act as non-magnetic impurities as far as the decrease is
concerned. The implication for the impurity doping effect in high
superconductors is also discussed.Comment: 12 pages and 1 figure, PlainTex, submitted to Mod. Phys. Lett. B, For
more information, please see "http://taesan.kaist.ac.kr/~yjkim
Rich variety of defects in ZnO via an attractive interaction between O-vacancies and Zn-interstitials
As the concentration of intrinsic defects becomes sufficiently high in
O-deficient ZnO, interactions between defects lead to a significant reduction
in their formation energies. We show that the formation of both O-vacancies and
Zn-interstitials becomes significantly enhanced by a strong attractive
interaction between them, making these defects an important source of n-type
conductivity in ZnO.Comment: 12 pages, 4 figure
Erratum: Dirichlet Forms and Dirichlet Operators for Infinite Particle Systems: Essential Self-adjointness
We reprove the essential self-adjointness of the Dirichlet operators of
Dirchlet forms for infinite particle systems with superstable and
sub-exponentially decreasing interactions.Comment: This is an erratum to the work appeared in J. Math. Phys. 39(12),
6509-6536 (1998
Molecular transistor coupled to phonons and Luttinger-liquid leads
We study the effects of electron-phonon interactions on the transport
properties of a molecular quantum dot coupled to two Luttinger-liquid leads. In
particular, we investigate the effects on the steady state current and DC noise
characteristics. We consider both equilibrated and unequilibrated on-dot
phonons. The density matrix formalism is applied in the high temperature
approximation and the resulting semi-classical rate equation is numerically
solved for various strengths of electron-electron interactions in the leads and
electron-phonon coupling. The current and the noise are in general smeared out
and suppressed due to intralead electron interaction. On the other hand, the
Fano factor, which measures the noise normalized by the current, is more
enhanced as the intralead interaction becomes stronger. As the electron-phonon
coupling becomes greater than order one, the Fano factor exhibits
super-Poissonian behaviour.Comment: 11 pages, 11 figure
A Perspective Towards NCIFA and CIFA in Named-Data Networking Architecture
Named-Data Networking (NDN) is the most promising architecture in the future Internet. NDN ensure high availability of contents and security of the data packet. However, it may disturb the stability and security in NDN routing such as Interest Flooding Attack (IFA). There are many existing detection and mitigation technique about IFA which labelled a non-collusive type of routing threats where it causes the PIT resources to exhausted and legitimate request could not perform in communication. Unfortunately, all the existing counter-measure mechanism could not defend the Collusive Interest Flooding Attack (CIFA). The attacks initiated with a satisfying interest and malicious data producer will reply to the corresponding request before the expiry of existing PIT entries in NDN router along the path. CIFA is classified as low rate intermittent attack which is very difficult in distinguish with legitimate requests. Thus, CIFA is more vulnerable and threatens than previous NCIFA. Moreover, there is no benchmark datasets or any public datasets to perform further experiments on detecting CIFA. Thus, there is a need to produce reliable datasets for future investigation in detection or mitigation relevant attacks in NDN
BRST Quantization of the Proca Model based on the BFT and the BFV Formalism
The BRST quantization of the Abelian Proca model is performed using the
Batalin-Fradkin-Tyutin and the Batalin-Fradkin-Vilkovisky formalism. First, the
BFT Hamiltonian method is applied in order to systematically convert a second
class constraint system of the model into an effectively first class one by
introducing new fields. In finding the involutive Hamiltonian we adopt a new
approach which is more simpler than the usual one. We also show that in our
model the Dirac brackets of the phase space variables in the original second
class constraint system are exactly the same as the Poisson brackets of the
corresponding modified fields in the extended phase space due to the linear
character of the constraints comparing the Dirac or Faddeev-Jackiw formalisms.
Then, according to the BFV formalism we obtain that the desired resulting
Lagrangian preserving BRST symmetry in the standard local gauge fixing
procedure naturally includes the St\"uckelberg scalar related to the explicit
gauge symmetry breaking effect due to the presence of the mass term. We also
analyze the nonstandard nonlocal gauge fixing procedure.Comment: 29 pages, plain Latex, To be published in Int. J. Mod. Phys.
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