19,794 research outputs found
Interplay of Kondo and superconducting correlations in the nonequilibrium Andreev transport through a quantum dot
Using the modified perturbation theory, we theoretically study the
nonequilibrium Andreev transport through a quantum dot coupled to normal and
superconducting leads (N-QD-S), which is strongly influenced by the Kondo and
superconducting correlations. From the numerical calculation, we find that the
renormalized couplings between the leads and the dot in the equilibrium states
characterize the peak formation in the nonequilibrium differential conductance.
In particular, in the Kondo regime, the enhancement of the Andreev transport
via a Kondo resonance occurs in the differential conductance at a finite bias
voltage, leading to an anomalous peak whose position is given by the
renormalized parameters. In addition to the peak, we show that the energy
levels of the Andreev bound states give rise to other peaks in the differential
conductance in the strongly correlated N-QD-S system. All these features of the
nonequilibrium transport are consistent with those in the recent experimental
results [R. S. Deacon {\it et al.}, Phys. Rev. Lett. {\bf 104}, 076805 (2010);
Phys. Rev. B {\bf 81}, 12308 (2010)]. We also find that the interplay of the
Kondo and superconducting correlations induces an intriguing pinning effect of
the Andreev resonances to the Fermi level and its counter position.Comment: 22 pages, 23 figure
Studies on Regioselective Binding Mode of Steroid Molecules in Homology Modeled Cytochrome P450-2C11
In this study, we investigated the regioselective binding mode of steroid molecules and structure requirements for steroid molecules for 16[alpha]-hydroxylation by Cytochrome P450-2C11. Docking study by using the homology Cytochrome P450-2C11 indicated that 16[alpha]-hydroxylation is favored with steroidal molecules possessing the following components, 1) a bent A-B ring configuration (5[beta]-reduced), 2) C-3[alpha]-hydroxyl group, 3) C-17[beta]-acetyl group, and 4) methyl group at both the C-18 and C-19. These respective steroid components requirements such as A-B ring configuration and functional groups at C-3 and C-17 were defined as the inhibitory contribution factor. Overall results by rat CYP2C11 revealed that steroidal structure requirements resulted in causing an effective inhibition of [^3^H]progesterone 16[alpha]-hydroxylation by the adult male rat liver microsome. As far as docking of homology modeled CYP2C11 against investigated steroids is concerned, they are docked at the active site superimposed with flurbiprofen. It was also found that the distance between heme iron and C16[alpha]-H was between 4 to 6 Å and that the related angle was in the range of 180±45°
Meservey-Tedrow-Fulde effect in a quantum dot embedded between metallic and superconducting electrodes
Magnetic field applied to the quantum dot coupled between one metallic and
one superconducting electrode can produce a similar effect as has been
experimentally observed by Meservey, Tedrow and Fulde [Phys. Rev. Lett. 25,
1270 (1970)] for the planar normal metal -- superconductor junctions. We
investigate the tunneling current and show that indeed the square root
singularities of differential conductance exhibit the Zeeman splitting near the
gap edge features V = +/- Delta/e. Since magnetic field affects also the in-gap
states of quantum dot it furthermore imposes a hyperfine structure on the
anomalous (subgap) Andreev current which has a crucial importance for a
signature of the Kondo resonance.Comment: 7 pages, 8 figure
Lattice study on two-color QCD with six flavors of dynamical quarks
We study the dynamics of SU(2) gauge theory with NF=6 Dirac fermions by means
of lattice simulation to investigate if they are appropriate to realization of
electroweak symmetry breaking. The discrete analogue of beta function for the
running coupling constant defined under the Schroedinger functional boundary
condition are computed on the lattices up to linear size of L/a=24 and preclude
the existence of infrared fixed point below 7.6. Gluonic observables such as
heavy quark potential, string tension, Polyakov loop suggest that the target
system is in the confining phase even in the massless quark limit.Comment: 7 pages, 9 figures, Proceedings of The 30th International Symposium
on Lattice Field Theory, June 24-29, 2012, Cairns, Australi
Magnetoresistance and surface roughness study of the initial growth of electrodeposited Co/Cu multilayers
The giant magnetoresistance (GMR) effect has been widely investigated on electrodeposited ferromagnetic/non-magnetic (FM/NM) multilayers generally containing a large number of bilayers. In most applications of the GMR effect, layered structures consisting of a relatively small number of consecutive FM and NM layers are used. It is of great interest, therefore, to investigate the initial stages of GMR multilayer film growth by electrodeposition. In the present work we have extended our previous studies on ED GMR multilayers to layered structures with a total thickness ranging from a few nanometers up to 70 nm. The evolution of the surface roughness and electrical transport properties of such ultrathin ED Co/Cu layered structures was investigated. Various layer combinations were produced including both Co and Cu either as starting or top layers in order (i) to see differences in the nucleation of the first layer and (ii) to trace out the effect of the so called exchange reaction. Special attention was paid to measure the field dependence of the magnetoresistance, MR(H) in order to derive information for the appearance of superparamagnetic regions in the magnetic layers. This proved to be helpful for monitoring the evolution of the layer microstructure at each step of the deposition sequence
Exact Phase Solutions of Nonlinear Oscillators on Two-dimensional Lattice
We present various exact solutions of a discrete complex Ginzburg-Landau
(CGL) equation on a plane lattice, which describe target patterns and spiral
patterns and derive their stability criteria. We also obtain similar solutions
to a system of van der Pol's oscillators.Comment: Latex 11 pages, 17 eps file
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