8,689 research outputs found
On the feasibility to study inverse proximity effect in a single S/F bilayer by Polarized Neutron Reflectometry
Here we report on a feasibility study aiming to explore the potential of
Polarized Neutron Reflectometry (PNR) for detecting the inverse proximity
effect in a single superconducting/ferromagnetic bilayer. Experiments,
conducted on the V(40nm)/Fe(1nm) S/F bilayer, have shown that experimental spin
asymmetry measured at T = 0.5TC is shifted towards higher Q values compared to
the curve measured at T = 1.5TC. Such a shift can be described by the
appearance in superconducting vanadium of magnetic sub-layer with thickness of
7 nm and magnetization of +0.8 kG.Comment: Changes in the 2nd version: small mistypes are corrected. Manuscript
submitted to JETP let. 4 pages, 2 figure
Sylow's theorem for Moufang loops
For finite Moufang loops, we prove an analog of the first Sylow theorem
giving a criterion of the existence of a p-Sylow subloop. We also find the
maximal order of p-subloops in the Moufang loops that do not possess p-Sylow
subloops.Comment: 21 page
QED theory of the nuclear recoil effect in atoms
The quantum electrodynamic theory of the nuclear recoil effect in atoms to
all orders in \alpha Z is formulated. The nuclear recoil corrections for atoms
with one and two electrons over closed shells are considered in detail. The
problem of the composite nuclear structure in the theory of the nuclear recoil
effect is discussed.Comment: 20 pages, 6 figures, Late
c-function and central charge of the sine-Gordon model from the non-perturbative renormalization group flow
In this paper we study the c-function of the sine-Gordon model taking explicitly into account the periodicity of the interaction potential. The integration of the c-function along trajectories of the non-perturbative renormalization group flow gives access to the central charges of the model in the fixed points. The results at vanishing frequency \u3b22, where the periodicity does not play a role, are retrieved and the independence on the cutoff regulator for small frequencies is discussed. Our findings show that the central charge obtained integrating the trajectories starting from the repulsive low-frequencies fixed points (\u3b22<8\u3c0) to the infra-red limit is in good quantitative agreement with the expected \u3b4c=1 result. The behavior of the c-function in the other parts of the flow diagram is also discussed. Finally, we point out that including also higher harmonics in the renormalization group treatment at the level of local potential approximation is not sufficient to give reasonable results, even if the periodicity is taken into account. Rather, incorporating the wave-function renormalization (i.e. going beyond local potential approximation) is crucial to get sensible results even when a single frequency is used
Magnetic proximity effects in V/Fe superconductor/ferromagnet single bilayer revealed by waveguide-enhanced polarized neutron reflectometry
Polarized neutron reflectometry is used to study the magnetic proximity
effect in a superconductor/ferromagnet (SC/FM) system of composition
Cu(32nm)/V(40nm)/Fe(1nm)/MgO. In contrast to previous studies, here a single
SC/FM bilayer, is studied and multilayer artefacts are excluded. The necessary
signal enhancement is achieved by waveguide resonance, i.e. preparing the
V(40nm)/Fe(1nm) SC/FM bilayer sandwiched by the highly reflective MgO substrate
and Cu top layer, respectively . A new magnetic state of the system was
observed at temperatures below 0.7 TC. manifested in a systematic change in the
height and width of the waveguide resonance peak. Upon increasing the
temperature from 0.7 TC to TC, a gradual decay of this state is observed,
accompanied by a 5% growth of the diffuse scattering. According to theoretical
studies, such behavior is the result of the magnetic proximity effect. Due to
the presence of the thin FM layer the superconducting electrons are polarized
and, as a result, near the SC/FM interface an additional magnetic layer appears
in the SC with thickness comparable to ksi, the coherence length of the
superconductor.Comment: Submitted to the Journal of Superconductivity and Novel Magnetism. 11
pages, 6 figures
An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr
The analysis of recent, extended multicolour CCD and archive photoelectric,
photographic and visual observations has revealed several important properties
of RZ Lyr, an RRab-type variable exhibiting large-amplitude Blazhko modulation.
On the time-base of \sim110 yr, a strict anticorrelation between the pulsation
and modulation period changes is established. The light curve of RZ Lyr shows a
remarkable bump on the descending branch in the small-amplitude phase of the
modulation, similarly to the light curves of bump Cepheids. We speculate that
the stellar structure temporally suits a 4:1 resonance between the periods of
the fundamental and one of the higher-order radial modes in this modulation
phase. The light-curve variation of RZ Lyr can be correctly fitted with a
two-modulation-component solution; the 121 d period of the main modulation is
nearly but not exactly four times longer than the period of the secondary
modulation component. Using the inverse photometric method, the variations in
the pulsation-averaged values of the physical parameters in different phases of
both modulation components are determined.Comment: 15 pages, 14 figures, 8 tables. Published in MNRAS, 2012. [v3]: Only
change: title correcte
Jordanian deformation of the open XXX-spin chain
The general solution to the reflection equation associated with the jordanian
deformation of the SL(2) invariant Yang R-matrix is found. The same K-matrix is
obtained by the special scaling limit of the XXZ-model with general boundary
conditions. The Hamiltonian with the boundary terms is explicitly derived
according to the Sklyanin formalism. We discuss the structure of the spectrum
of the deformed XXX-model and its dependence on the boundary conditions.Comment: 13 pages; typos correcte
Jets in deep-inelastic scattering at HERA
Jet cross sections in deep-inelastic scattering over a wide region of phase
space have been measured at HERA. These cross section measurements provide a
thorough test of the implementation of Quantum Chromodynamics in
next-to-leading order (NLO) calculations. They also provide the opportunity to
test the consistency of the gluon distribution in the proton as extracted from
(mainly) inclusive DIS measurements. Comparison of the cross sections with NLO
enables accurate extractions of the strong coupling constant, , to be
made, several of which are reported here.Comment: Talk presented at "New Trends in HERA Physics", Ringberg Workshop,
June 2001. 13pages, 12figure
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