Femtosecond spectroscopy of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">YBa</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Cu</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://w

Чекалин, С. В.; Farztdinov, V. M.; Golovlyov, V. V.; Letokhov, V. S.; Lozovik, Yu. E.; Matveets, Yu. A.; Степанов, А. Л.

doi:10.1103/physrevlett.67.3860

Cited by 69 publications

(36 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7 and 8͒ found a relaxation process below T c , which is distinct from the equilibration of hot carriers in the normal state. A relatively strong e-ph coupling, Ӎ 0.9, 8 and a rapid decrease in the photoresponse decay rate with decreasing temperature 15 were found in YBa 2 Cu 3 O 6.5 , and the phonon bottleneck 12,[16][17][18] or a biparticle recombination 15,19 were observed below T c . More recently, a time-resolved photoemission spectroscopy 20 and the standard pump-probe optical measurements 21 have been performed on Bi 2 Sr 2 CaCu 2 O 8+␦ .…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Electron relaxation in metals: Theory and exact analytical solutions

2008

View full text Add to dashboard Cite

The nonequilibrium dynamics of electrons is of a great experimental and theoretical value, providing important microscopic parameters of the Coulomb and electron-phonon interactions in metals and other cold plasmas. Because of the mathematical complexity of collision integrals, theories of electron relaxation often rely on the assumption that electrons are in a "quasiequilibrium" ͑QE͒ with a time-dependent temperature, or on the numerical integration of the time-dependent Boltzmann equation. We transform the integral Boltzmann equation to a partial differential Schrödinger-type equation with imaginary time in a one-dimensional "coordinate" space reciprocal to energy which allows for exact analytical solutions in both cases of electron-electron and electron-phonon relaxations. The exact relaxation rates are compared with the QE relaxation rates at high and low temperatures.

show abstract

Section: Introductionmentioning

confidence: 97%

“…[6][7][8][9][10][11][12] The pump-probe experiments are routinely analyzed in the framework of the so-called twotemperature model ͑TTM͒. 13,14 The model is based on the assumption that electrons and phonons are in a thermal quasiequilibrium ͑QE͒ with two different time-dependent temperatures T e ͑t͒ and T l ͑t͒.…”

Section: Introductionmentioning

confidence: 99%

Electron relaxation in metals: Theory and exact analytical solutions

2008

View full text Add to dashboard Cite

show abstract

“…They have been used to study many phenomena of fundamental and applied interest such as optical orientation of spin, 1 ultrafast demagnetization, 2 and ultrafast excitation of coherent phonons, 3 and magnons. 4 Their potential for materials characterization is illustrated by measurements of the electronphonon coupling constant in high T c superconductors 5 and metals, 6 hot electron linear and angular momentum relaxation times 7 and nonlinear susceptibility tensor components 8 in metals, and the spin wave mode spectrum of nanomagnets. 9 Significant efforts have been devoted recently to investigations of the kinetics of electron-electron and electronphonon thermalization in metals, deduced from measurements of the transient ͑differential͒ reflectivity and/or transmission.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic study of optically induced ultrafast electron dynamics in gold

et al. 2007

View full text Add to dashboard Cite

Using a supercontinuum pulse as a probe, we have measured the transient reflectivity spectra of a thin film of gold for different values of the pump-probe time delay. The wavelength x at which the measured transient reflectivity changes sign has been found to depend upon the time delay, leading to bipolar time resolved signals. The time dependence of x has been shown to be consistent with calculations that take into account the full dependence of the reflectivity upon the electron occupation number, and to contradict qualitatively a model in which the signal is assumed to be directly proportional to the occupation number. The shift of x has been found to persist at time delays that are much longer than the time required for the electrons to thermalize. Therefore the bipolar reflectivity signals do not necessarily contain a contribution from nonthermalized electrons, as has been previously assumed.

show abstract

“…The values of the relaxation times in high-T c superconductors are not well established. If we estimate τ in ∼ 10ps at T ∼ 20K in YBaCuO [23], we get the region of applicability of our theory V < 100µV . We also note that the length of the junction is limited by the diffusion length D N τ N e−e that is determined by the electron-electron relaxation time in the normal metal, τ N e−e .…”

mentioning

confidence: 99%

“…At eV > 1/τ in , the same considerations lead to a non-analytic V -dependence of the G DN D (V ) ∝ V −1/2 , which can be obtained from Eq. (23) by the substitution τ in → 1/2eV .…”

mentioning

confidence: 99%

Conductance ofd-Wave Superconductor/Normal Metal/d-Wave Superconductor Junctions

Pesin

Andreev²,

Spivak³

2008

Phys. Rev. Lett.

View full text Add to dashboard Cite

We develop a theory of the conductance of superconductor/normal metal/superconductor junctions in the case where the superconducting order parameter has d-wave symmetry. At low temperature the conductance is proportional to the square root of the inelastic electron relaxation time in the bulk of the superconductor. As a result it turns out to be much larger than the conductance of the normal part of the junction.PACS numbers: 74.45.+c, 74.50.+r, 74.20.Rp At small voltages V , the current I through a superconductor/normal metal/superconductor (SNS) junction can be written asHere φ is the phase difference between the superconductors, and J(φ) is a periodic function of φ with period 2π. The time dependence of φ is given by the Josephson relation:The first term in Eq.(1), describing the Josephson current, has been the subject of intensive experimental and theoretical studies over several decades, since the discovery of the Josephson effect. The second term, representing the dissipative current, has attracted relatively little attention, both on the theoretical and experimental sides. In the context of SNS junctions with s-wave symmetry of the order parameter in the leads, this problem was considered theoretically in [1][2][3][4][5][6][7], and experimentally in [8]. The common result of these works is that at low temperatures the conductance of the system is proportional to the inelastic relaxation time in the normal metal. A theory of conductance of a junction in the case when the superconducting order parameter has d-wave symmetry has not been developed. In this paper we show that at low temperatures T the conductance, G DN D , is proportional to the square root of the energy relaxation time in the bulk of superconductor, τ in , and that it is much larger than the conductance G N of the normal piece of the junction.The origin of the leading low-temperature contribution to G DN D is similar to the Debye relaxation mechanism in dielectrics, or the Mandelstam-Leontovich mechanism for sound absorption in liquids with internal degrees of freedom [9]. Due to the proximity effect the single particle density of states in the normal region, ν N (ε, φ), becomes ε and φ-dependent. Here ε is the energy of quasiparticle. According to Eq. (2), ν N (ε, φ(t)) changes in time. In the adiabatic approximation the electron population follows the motion of the levels. As a result, the quasiparticle distribution function becomes nonequilibrium. Its relaxation leads to the entropy production, and therefore contributes to the conductance:The equation for the entropy production readṡwhere f (ε, r, t) is the quasiparticle distribution function, f th (ε, r, t) = tanh ε/2T is the equilibrium distribution function, τ in is the inelastic relaxation time, D ij (ε) is the diffusion coefficient, and ν is the reduced density of states, measured in the units of the normal state density of states, ν 0 . We assume that the latter is the same in both metals.The kinetic equation describing the dynamics of quasiparticles has the following form: ν ∂f ∂...

show abstract

Femtosecond spectroscopy ofYBa2Cu3
С. В. Чекалин
¹
,
V. M. Farztdinov
²
,
V. V. Golovlyov
³

et al.

Cited by 69 publications

References 21 publications

Electron relaxation in metals: Theory and exact analytical solutions

Electron relaxation in metals: Theory and exact analytical solutions

Spectroscopic study of optically induced ultrafast electron dynamics in gold

Conductance ofd-Wave Superconductor/Normal Metal/d-Wave Superconductor Junctions

Contact Info

Product

Resources

About

Femtosecond spectroscopy ofYBa2Cu3С. В. Чекалин1, V. M. Farztdinov2, V. V. Golovlyov3 et al.

Cited by 69 publications

References 21 publications

Electron relaxation in metals: Theory and exact analytical solutions

Electron relaxation in metals: Theory and exact analytical solutions

Spectroscopic study of optically induced ultrafast electron dynamics in gold

Conductance ofd-Wave Superconductor/Normal Metal/d-Wave Superconductor Junctions

Contact Info

Product

Resources

About

Femtosecond spectroscopy ofYBa2Cu3
С. В. Чекалин
¹
,
V. M. Farztdinov
²
,
V. V. Golovlyov
³

et al.