2,355 research outputs found
Electronic Raman scattering in Tl2Ba2CuO6+x: symmetry of the order parameter, oxygen doping effects, and normal state scattering
Single crystals of the optimally doped, moderately and strongly overdoped
high temperature superconductor Tl2Ba2CuO6+x (Tl-2201) with Tc=80, 56 and 30K,
respectively, have been investigated by polarized Raman scattering. By taking
the peak position of the B_1g component of electronic Raman scattering as
2Delta_0 we found that the reduced gap value (2Delta_0/k_BT_c) strongly
decreases with increasing doping. The behavior of the low frequency scattering
for the B_1g and B_2g scattering components is similar for optimally doped and
overdoped crystals and can be described by a w^3 - and w -law, respectively,
which is consistent with a d-wave symmetry of the order parameter. In contrast
to the optimally doped Tl-2201 in both, moderately and strongly overdoped
Tl-2201, the relative (compared to the B_1g) intensity of the A_1g scattering
component is suppressed. We suggest that the van Hove singularity is
responsible for the observed changes of Raman intensity and reduced gap value
with doping. Electronic Raman scattering in the normal state is discussed in
the context of the scattering from impurities and compared to the existing
infrared data. The scattering rate evaluated from the Raman measurements is
smaller for the overdoped samples, compared to the moderately overdoped
samples.Comment: 7 pages, 7 figure
Π Π΅Π°Π»ΠΈΠ·Π°ΡΠΈΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΠΎΠ² ΠΏΠΎΠ΄ΡΡΠ΅ΡΠ° ΡΠΎΡΠ΅ΠΊ Π² ΡΠΊΠΎΠ±ΠΈΠ°Π½Π°Ρ Π³ΠΈΠΏΠ΅ΡΡΠ»Π»ΠΈΠΏΡΠΈΡΠ΅ΡΠΊΠΈΡ ΠΊΡΠΈΠ²ΡΡ ΡΠΎΠ΄Π° 2, ΠΎΡΠ½ΠΎΠ²Π°Π½Π½ΡΡ Π½Π° ΠΏΠ°ΡΠ°Π΄ΠΎΠΊΡΠ΅ Π΄Π½Π΅ΠΉ ΡΠΎΠΆΠ΄Π΅Π½ΠΈΡ
ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π° ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½Π°Ρ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΠ½Π°Ρ ΡΠ΅Π°Π»ΠΈΠ·Π°ΡΠΈΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° ΠΠΎΠ΄ΡΠΈ β Π¨ΠΎΡΡΠ° ΠΈ Π΅Π³ΠΎ ΠΌΠΎΠ΄ΠΈΡΠΈΠΊΠ°ΡΠΈΠΈ ΠΡΠ»Π±ΡΠ°ΠΉΡΠ° β Π ΡΠΏΡΠ°Ρ Π΄Π»Ρ ΠΏΠΎΠ΄ΡΡΡΡΠ° ΡΠΎΡΠ΅ΠΊ Π² ΡΠΊΠΎΠ±ΠΈΠ°Π½Π°Ρ
Π³ΠΈΠΏΠ΅-ΡΡΠ»Π»ΠΈΠΏΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΊΡΠΈΠ²ΡΡ
. ΠΡΠΈ Π°Π»Π³ΠΎΡΠΈΡΠΌΡ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»ΡΡΡ ΡΠΎΠ±ΠΎΠΉ Π²Π΅ΡΡΠΈΠΈ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° ΠΠ°ΡΡΠΎ β Π§Π°ΠΎ β Π¦ΡΠ΄ΠΆΠΈΡ Ρ ΠΌΠ°Π»ΡΠΌ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΏΠ°ΠΌΡΡΠΈ ΠΈ ΡΠ΅Π°Π»ΠΈΠ·ΡΡΡ ΡΡΡΠ°ΡΠ΅Π³ΠΈΡ ΠΠ΅Π»ΡΡΠΎΠ½Π΄Π° β Π¨Π΅Π½ΠΊΡΠ° Π±ΠΎΠ»ΡΡΠΈΡ
ΠΈ ΠΌΠ°Π»ΡΡ
ΡΠ°Π³ΠΎΠ². ΠΡΠ²ΠΎΠ΄ΠΈΡΡΡ ΠΎΠΏΡΠΈΠΌΠ°Π»ΡΠ½ΡΠΉ ΡΠ°Π·ΠΌΠ΅Ρ ΠΏΠ°ΠΌΡΡΠΈ, ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡΠΈΠΉ ΠΌΠΈΠ½ΠΈΠΌΠΈΠ·ΠΈΡΠΎΠ²Π°ΡΡ Π²ΡΠ΅ΠΌΡ ΡΠ°Π±ΠΎΡΡ ΡΠΊΠ°Π·Π°Π½Π½ΡΡ
Π°Π»Π³ΠΎΡΠΈΡΠΌΠΎΠ² ΠΈ ΠΏΠΎΠ»ΡΡΠΈΡΡ Π½Π° ΠΏΡΠ°ΠΊΡΠΈΠΊΠ΅ ΠΎΠΆΠΈΠ΄Π°Π΅ΠΌΠΎΠ΅ Π²ΡΠ΅ΠΌΡ ΠΈΡ
ΡΠ°Π±ΠΎΡΡ, Π±Π»ΠΈΠ·ΠΊΠΎΠ΅ ΠΊ ΡΠ΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΎΡΠ΅Π½ΠΊΠ°ΠΌ 2;45pN ΠΈ 2;38pN Π΄Π»Ρ Π°Π»Π³ΠΎΡΠΈΡΠΌΠΎΠ² ΠΠΎΠ΄ΡΠΈ β Π¨ΠΎΡΡΠ° ΠΈ ΠΡΠ»Π±ΡΠ°ΠΉΡΠ° β Π ΡΠΏΡΠ°Ρ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΠΎ. ΠΠ΄Π΅ΡΡ N β ΡΠ°Π·ΠΌΠ΅Ρ Π΄Π²ΡΠΌΠ΅ΡΠ½ΠΎΠΉ ΠΎΠ±Π»Π°ΡΡΠΈ ΠΏΠΎΠΈΡΠΊΠ°, ΡΠ°Π²Π½ΡΠΉ ΠΏΠΎΡΡΠ΄ΠΊΡ ΡΠΊΠΎΠ±ΠΈΠ°Π½Π° ΠΊΡΠΈΠ²ΠΎΠΉ, ΡΠΌΠ΅Π½ΡΡΠ΅Π½Π½ΠΎΠΌΡ Π² m ΡΠ°Π· Ρ ΠΏΠΎΠΌΠΎΡΡΡ Π΄ΡΡΠ³ΠΈΡ
ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ². ΠΡΠ΅Π΄Π»Π°Π³Π°Π΅ΠΌΠ°Ρ ΡΠ΅Π°Π»ΠΈΠ·Π°ΡΠΈΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΠΎΠ² ΠΈΠΌΠ΅Π΅Ρ ΠΌΠ½ΠΎΠ³ΠΎΠΏΠΎΡΠΎΡΠ½ΡΠΉ ΡΠ΅ΠΆΠΈΠΌ ΡΠ°Π±ΠΎΡΡ. ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Π° ΡΡΠ°ΡΠΈΡΡΠΈΡΠ΅ΡΠΊΠ°Ρ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΡ Π²ΡΠ΅ΠΌΠ΅Π½ΠΈ ΡΠ°Π±ΠΎΡΡ ΠΎΡ ΡΠ°Π·ΠΌΠ΅ΡΠ° Π²Ρ
ΠΎΠ΄Π½ΡΡ
Π΄Π°Π½Π½ΡΡ
. ΠΠ°Π½Π½Π°Ρ ΡΠ΅Π°Π»ΠΈΠ·Π°ΡΠΈΡ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° ΠΡΠ»Π±ΡΠ°ΠΉΡΠ° β Π ΡΠΏΡΠ°Ρ Π΄Π»Ρ ΡΠ°Π·ΠΌΠ΅ΡΠ½ΠΎΡΡΠΈ 2 ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΏΠ΅ΡΠ²ΠΎΠΉ ΠΎΠΏΡΠ±Π»ΠΈΠΊΠΎΠ²Π°Π½Π½ΠΎΠΉ ΠΌΠ½ΠΎΠ³ΠΎΠΏΠΎΡΠΎΡΠ½ΠΎΠΉ ΡΠ΅Π°Π»ΠΈΠ·Π°ΡΠΈΠ΅ΠΉ ΡΡΠΎΠ³ΠΎ Π°Π»Π³ΠΎΡΠΈΡΠΌΠ° Ρ ΠΎΡΠΊΡΡΡΡΠΌ ΠΈΡΡ
ΠΎΠ΄Π½ΡΠΌ ΠΊΠΎΠ΄ΠΎΠΌ
A flexible polymer chain in a critical solvent: Coil or globule?
We study the behavior of a flexible polymer chain in the presence of a
low-molecular weight solvent in the vicinity of a liquid-gas critical point
within the framework of a self-consistent field theory. The total free energy
of the dilute polymer solution is expressed as a function of the radius of
gyration of the polymer and the average solvent number density within the
gyration volume at the level of the mean-field approximation. Varying the
strength of attraction between polymer and solvent we show that two
qualitatively different regimes occur at the liquid-gas critical point. In case
of weak polymer-solvent interactions the polymer chain is in a globular state.
On the contrary, in case of strong polymer-solvent interactions the polymer
chain attains an expanded conformation. We discuss the influence of the
critical solvent density fluctuations on the polymer conformation. The reported
effect could be used to excert control on the polymer conformation by changing
the thermodynamic state of the solvent. It could also be helpful to estimate
the solvent density within the gyration volume of the polymer for drug delivery
and molecular imprinting applications
On the Ado Theorem for finite Lie conformal algebras with Levi decomposition
We prove that a finite torsion-free conformal Lie algebra with a splitting
solvable radical has a finite faithful conformal representation.Comment: 11 page
Multivalued current-phase relationship in a.c. Josephson effect for a three-dimensional Weyl semimetal WTe
We experimentally study electron transport between two superconducting indium
leads, coupled to a single WTe crystal, which is a three-dimensional Weyl
semimetal. We demonstrate Josephson current in long 5~m In-WTe-In
junctions, as confirmed by the observation of integer (1,2,3) and fractional
(1/3, 1/2, 2/3) Shapiro steps under microwave irradiation. Demonstration of
fractional a.c. Josephson effect indicates multivalued character of the
current-phase relationship, which we connect with Weyl topological surface
states contribution to Josephson current. In contrast to topological insulators
and Dirac semimetals, we do not observe periodicity in a.c. Josephson
effect for WTe at different frequencies and power, which might reflect
chiral character of the Fermi arc surface states in Weyl semimetal.Comment: the text is seriously corrected. arXiv admin note: text overlap with
arXiv:1801.0955
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