93 research outputs found
Measuring the gap in ARPES experiments
Angle-resolved photoemission spectroscopy (ARPES) is considered as the only
experimental tool from which the momentum distribution of both the
superconducting and pseudo-gap can be quantitatively derived. The binding
energy of the leading edge of the photoemission spectrum, usually called the
leading edge gap (LEG), is the model-independent quantity which can be measured
in the modern ARPES experiments with the very high accuracy--better than 1 meV.
This, however, may be useless as long as the relation between the LEG and the
real gap is unknown. We present a systematic study of the LEG as a function of
a number of physical and experimental parameters. The absolute gap values which
have been derived from the numerical simulation prove, for example that the
nodal direction in the underdoped Bi-2212 in superconducting state is really
the node--the gap is zero. The other consequences of the simulations are
discussed.Comment: revtex4, 9 pages, 6 figure
ARPES on high-temperature superconductors: simplicity vs. complexity
A notable role in understanding of microscopic electronic properties of high temperature superconductors
(HTSC) belongs to angle resolved photoemission spectroscopy (ARPES). This technique
supplies a direct window into the reciprocal space of solids: the momentumβenergy space
where quasiparticles (electrons dressed in clouds of interactions) dwell. Any interaction in the
electronic system, e.g., superconducting pairing, leads to modification of the quasiparticle spectrumβto
redistribution of the spectral weight over the momentumβenergy space probed by
ARPES. Continued development of the technique had the effect that the picture seen through the
ARPES window became clearer and sharper until the complexity of the electronic band structure
of the cuprates had been resolved. Now, in the doping range optimal for superconductivity, the
cuprates much resemble a normal metal with well-predicted electronic structure, though with
rather strong electronβelectron interaction. This principal disentanglement of the complex physics
from complex structure reduced the mystery of HTSC to the tangible problem of the interaction responsible
for quasiparticle formation. Here we present a short overview of resent ARPES results,
which, we believe, suggest a way to resolve the HTSC puzzle
An ARPES view on the high-Tc problem: phonons vs spin-fluctuations
We review the search for a mediator of high-Tc superconductivity focusing on
ARPES experiment. In case of HTSC cuprates, we summarize and discuss a
consistent view of electronic interactions that provides natural explanation of
both the origin of the pseudogap state and the mechanism for high temperature
superconductivity. Within this scenario, the spin-fluctuations play a decisive
role in formation of the fermionic excitation spectrum in the normal state and
are sufficient to explain the high transition temperatures to the
superconducting state while the pseudogap phenomenon is a consequence of a
Peierls-type intrinsic instability of electronic system to formation of an
incommensurate density wave. On the other hand, a similar analysis being
applied to the iron pnictides reveals especially strong electron-phonon
coupling that suggests important role of phonons for high-Tc superconductivity
in pnictides.Comment: A summary of the ARPES part of the Research Unit FOR538,
http://for538.wmi.badw.d
Diode Based on Amorphous SiC
Diode structure on the basis of amorphous silicon carbide and p-type polycrystalline silicon (Eurosolar) were obtained with magnetron RF-nonreactive sputtering method from solid-phase target in argon atmosphere.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3365
About the relation between the quasiparticle Green's function in cuprates obtained from ARPES data and the magnetic susceptibility
Angle resolved photoemission spectroscopy (ARPES) provides a detailed view of
the renormalized band structure in cuprates and, consequently, is a key to the
self-energy and the quasiparticle Green's function. Such information gives a
clue to the comparison of ARPES with scanning tunneling microscopy, inelastic
neutron scattering (INS), and Raman scattering data. Here we touch on a
potential possibility of such a comparison with the dynamical magnetic
susceptibility measured in INS experiments. Calculations based on the
experimentally measured quasiparticle self-energies in cuprates lead to the
estimated magnetic susceptibility response with many-body effects taken into
account.Comment: Will be presented at the M2S-HTSC-VIII conference in Dresde
From tunneling to photoemission: correlating two spaces
Correlating the data measured by tunneling and photoemission spectroscopies
is a long-standing problem in condensed matter physics. The quasiparticle
interference, recently discovered in high-Tc cuprates, reveals a possibility to
solve this problem. Application of modern phase retrieval algorithms to Fourier
transformed tunneling data allows to recover the distribution of the
quasiparticle spectral weight in the reciprocal space of solids measured
directly by photoemission. This opens a direct way to unify these two powerful
techniques and may help to solve a number of problems related with space/time
inhomogeneities predicted in strongly correlated electron systems.Comment: more info at http://www.imp.kiev.ua/~kord/AC-ARPES/index.htm
Origin of the shadow Fermi surface in Bi-based cuprates
We used angle-resolved photoemission spectroscopy to study the shadow Fermi
surface in one layer Bi2Sr1.6La0.4CuO6+delta and two layer
(Bi,Pb)2Sr2CaCu2O8+delta. We find the shadow band to have the same peakwidth
and dispersion as the main band. In addition, the shadow band/main band
intensity ratio is found to be binding energy independent. Consequently, it is
concluded that the shadow bands in Bi-based HTSC do not originate from
antiferromagnetic interactions but have a structural origin.Comment: 10 pages, 2 figure
Study of the radiochemical and thermal conversions mechanism in products of processing of grapes
The extraction of biologically active substance was carried out with help of combination of the physical factors:
various conditions of temperature (40, 50, 60Β°Π‘) and pressure of vacuum drying (8, 14, 16 mm Hg), and also various
radiation doses by electrons with energy 12 ΠeV (10, 20, 40 kGy). The investigations of dynamics of definition of
extract acidity and formation level of intermediate active products are carried out. It was established that the
modification of properties of grape raw material depends on type of grapes, requirements of vacuum drying and
radiation dose by electrons.ΠΠΊΡΡΡΠ°ΠΊΡΡΡ Π±ΡΠΎΠ»ΠΎΠ³ΡΡΠ½ΠΎ Π°ΠΊΡΠΈΠ²Π½ΠΈΡ
ΡΠ΅ΡΠΎΠ²ΠΈΠ½ Π±ΡΠ»ΠΎ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ Π·Π° Π΄ΠΎΠΏΠΎΠΌΠΎΠ³ΠΎΡ ΠΊΠΎΠΌΠ±ΡΠ½Π°ΡΡΡ ΡΡΠ·ΠΈΡΠ½ΠΈΡ
ΡΠ°ΠΊΡΠΎΡΡΠ²:
ΡΡΠ·Π½Ρ ΡΠ΅ΠΆΠΈΠΌΠΈ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠΈ (40, 50, 60Β°Π‘) Ρ ΡΠΈΡΠΊΡ Π²Π°ΠΊΡΡΠΌΠ½ΠΎΠ³ΠΎ ΡΡΡΡΠ½Π½Ρ (8, 14, 16 ΠΌΠΌ Hg), Π° ΡΠ°ΠΊΠΎΠΆ ΡΡΠ·Π½Ρ Π΄ΠΎΠ·ΠΈ
ΠΎΠΏΡΠΎΠΌΡΠ½Π΅Π½Π½Ρ Π΅Π»Π΅ΠΊΡΡΠΎΠ½Π°ΠΌΠΈ Π· Π΅Π½Π΅ΡΠ³ΡΡΡ 12 ΠΠ΅Π (10, 20, 40 ΠΊΠΡ). ΠΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ Π΄ΠΎΡΠ»ΡΠ΄ΠΆΠ΅Π½Π½Ρ Π΄ΠΈΠ½Π°ΠΌΡΠΊΠΈ ΠΊΠΈΡΠ»ΠΎΡΠ½ΠΎΡΡΡ
Π΅ΠΊΡΡΡΠ°ΠΊΡΡΠ² Ρ ΡΡΠ²Π½Ρ ΡΡΠ²ΠΎΡΠ΅Π½Π½Ρ ΠΏΡΠΎΠΌΡΠΆΠ½ΠΈΡ
Π°ΠΊΡΠΈΠ²Π½ΠΈΡ
ΠΏΡΠΎΠ΄ΡΠΊΡΡΠ². ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΠΎ Π·ΠΌΡΠ½Π° Π²Π»Π°ΡΡΠΈΠ²ΠΎΡΡΠ΅ΠΉ Π²ΠΈΠ½ΠΎΠ³ΡΠ°Π΄Π½ΠΎΡ
ΡΠΈΡΠΎΠ²ΠΈΠ½ΠΈ Π·Π°Π»Π΅ΠΆΠΈΡΡ Π²ΡΠ΄ ΡΠΎΡΡΡ Π²ΠΈΠ½ΠΎΠ³ΡΠ°Π΄Ρ, ΡΠΌΠΎΠ² Π²Π°ΠΊΡΡΠΌΠ½ΠΎΠ³ΠΎ ΡΡΡΡΠ½Π½Ρ Ρ Π΄ΠΎΠ·ΠΈ ΠΎΠΏΡΠΎΠΌΡΠ½Π΅Π½Π½Ρ Π΅Π»Π΅ΠΊΡΡΠΎΠ½Π°ΠΌΠΈ.ΠΠΊΡΡΡΠ°ΠΊΡΠΈΡ Π±ΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈ Π°ΠΊΡΠΈΠ²Π½ΡΡ
Π²Π΅ΡΠ΅ΡΡΠ² Π±ΡΠ»Π° ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½Π° Ρ ΠΏΠΎΠΌΠΎΡΡΡ ΠΊΠΎΠΌΠ±ΠΈΠ½Π°ΡΠΈΠΈ ΡΠΈΠ·ΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ°ΠΊΡΠΎΡΠΎΠ²: ΡΠ°Π·Π»ΠΈΡΠ½ΡΠ΅ ΡΠ΅ΠΆΠΈΠΌΡ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΡ (40, 50, 60Β°Π‘) ΠΈ Π΄Π°Π²Π»Π΅Π½ΠΈΡ Π²Π°ΠΊΡΡΠΌΠ½ΠΎΠΉ ΡΡΡΠΊΠΈ (8, 14, 16 ΠΌΠΌ Hg), Π°
ΡΠ°ΠΊΠΆΠ΅ ΡΠ°Π·Π»ΠΈΡΠ½ΡΠ΅ Π΄ΠΎΠ·Ρ ΠΎΠ±Π»ΡΡΠ΅Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΎΠ½Π°ΠΌΠΈ Ρ ΡΠ½Π΅ΡΠ³ΠΈΠ΅ΠΉ 12 ΠΡΠ (10, 20, 40 ΠΊΠΡ). ΠΡΠΎΠ²Π΅Π΄Π΅Π½Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ
Π΄ΠΈΠ½Π°ΠΌΠΈΠΊΠΈ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΊΠΈΡΠ»ΠΎΡΠ½ΠΎΡΡΠΈ ΡΠΊΡΡΡΠ°ΠΊΡΠΎΠ² ΠΈ ΡΡΠΎΠ²Π½Ρ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ ΠΏΡΠΎΠΌΠ΅ΠΆΡΡΠΎΡΠ½ΠΎ-Π°ΠΊΡΠΈΠ²Π½ΡΡ
ΠΏΡΠΎΠ΄ΡΠΊΡΠΎΠ².
ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ ΡΠ²ΠΎΠΉΡΡΠ² Π²ΠΈΠ½ΠΎΠ³ΡΠ°Π΄Π½ΠΎΠ³ΠΎ ΡΡΡΡΡ Π·Π°Π²ΠΈΡΠΈΡ ΠΎΡ ΡΠΎΡΡΠ° Π²ΠΈΠ½ΠΎΠ³ΡΠ°Π΄Π°, ΡΡΠ»ΠΎΠ²ΠΈΠΉ Π²Π°ΠΊΡΡΠΌΠ½ΠΎΠΉ ΡΡΡΠΊΠΈ
ΠΈ Π΄ΠΎΠ·Ρ ΠΎΠ±Π»ΡΡΠ΅Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΎΠ½Π°ΠΌΠΈ
Mass-renormalized electronic excitations at (, 0) in the superconducting state of
Using high-resolution angle-resolved photoemission spectroscopy on
, we have made the first observation of a
mass renormalization or "kink" in the E vs. dispersion relation
localized near . Compared to the kink observed along the nodal
direction, this new effect is clearly stronger, appears at a lower energy near
40 meV, and is only present in the superconducting state. The kink energy scale
defines a cutoff below which well-defined quasiparticle excitations occur. This
effect is likely due to coupling to a bosonic excitation, with the most
plausible candidate being the magnetic resonance mode observed in inelastic
neutron scattering
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