Nonequilibrium superconductivity

Chang, Joon-Hyuk; Scalapino, D. J.

doi:10.1007/bf00116228

Cited by 110 publications

(59 citation statements)

References 33 publications

(22 reference statements)

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“…We will show that such temporal oscillations can significantly enhance T c even if the time-averaged attraction remains constant, see Figs. 1 (right) and 6.…”

Section: Introductionmentioning

confidence: 99%

Theory of parametrically amplified electron-phonon superconductivity

et al. 2017

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Ultrafast optical manipulation of ordered phases in strongly correlated materials is a topic of significant theoretical, experimental, and technological interest. Inspired by a recent experiment on light-induced superconductivity in fullerenes [Mitrano et al., Nature 530, 2016], we develop a comprehensive theory of light-induced superconductivity in driven electron-phonon systems with lattice nonlinearities. In analogy with the operation of parametric amplifiers, we show how the interplay between the external drive and lattice nonlinearities lead to significantly enhanced effective electron-phonon couplings. We provide a detailed and unbiased study of the nonequilibrium dynamics of the driven system using the real-time Green's function technique. To this end, we develop a Floquet generalization of the Migdal-Eliashberg theory and derive a numerically tractable set of quantum Floquet-Boltzmann kinetic equations for the coupled electron-phonon system. We study the role of parametric phonon generation and electronic heating in destroying the transient superconducting state. Finally, we predict the transient formation of electronic Floquet bands in time-and angle-resolved photoemission spectroscopy experiments as a consequence of the proposed mechanism.

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“…We will show that such temporal oscillations can significantly enhance T c even if the time-averaged attraction remains constant, see Figs. 1 (right) and 6.…”

Section: Introductionmentioning

confidence: 99%

Theory of parametrically amplified electron-phonon superconductivity

et al. 2017

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“…3. Calculated phonon spectrum at finite injection in the limit ,~/% = 0 culated spectra for finite phonon trapping are presented in [26]. According to this analysis the structures, we expect in the primary spectra, are:…”

Section: _ ! !mentioning

confidence: 89%

“…A further structure arises only if the injected primary quasiparticle density is not too small compared with the excitation density; i.e; a cut-off step in the recombination spectrum at energy g2= 2(e U G-AG) [26]. An essential feature of the structures A, C, D is, that their spectral positions can be tuned by variation of the generator voltage.…”

Section: D)mentioning

confidence: 99%

Analysis of the phonon spectrum emitted by superconducting Al-tunneling junctions at high quasiparticle injection rates

Welte

Eisenmenger

1981

Z. Physik B - Condensed Matter

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The phonon spectrum emitted by superconducting Al-tunneling junctions is analyzed by experiments, in which two junctions of different energy gaps are used as phonon generator and detector. The energy gap of the Al-films is varied by the evaporation conditions. The experiments show clearly that the phonon spectrum and the quasiparticle distributions in the generator are strongly nonthermal and depend markedly on the primary tunneling injection. At high injection rates also significant consequences of gap reductions and instabilities are observed.

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“…2.7, even though there is a net increase in mean energy of the quasiparticle distribution. Also, an actual decrease in the total number of quasiparticles results because recombination is more rapid at higher energies [81]. It is important to note that there is a minimum frequency for the enhancement effect to take place because at lower frequencies, the rf current will only serve to break pairs and weaken superconductivity.…”

Section: Enhancement By Microwave Irradiationmentioning

confidence: 99%

Spin-polarized quasiparticle transport in cuprate superconductors

Huang

Yeh

2002

Phys. Rev. B

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The effects of spin-polarized quasiparticle transport in superconducting YBa 2 Cu 3 O 7Ϫ␦ ͑YBCO͒ epitaxial films are investigated by means of current injection into perovskite ferromagnet-insulator-superconductor ͑F-I-S͒ heterostructures. These effects are compared with the injection of simple quasiparticles into control samples of perovskite nonmagnetic metal-insulator-superconductor ͑N-I-S͒. Systematic studies of the critical current density (J c ) as a function of the injection current density (J in j ), temperature (T), and the thickness ͑d͒ of the superconductor reveal drastic differences between the F-I-S and N-I-S heterostructures, with strong suppression of J c and a rapidly increasing characteristic transport length near the superconducting transition temperature T c only in the F-I-S samples. The temperature dependence of the efficiency (ϵ⌬J c /J in j ; ⌬J c : the suppression of critical current due to finite J in j ͒ in the F-I-S samples is also in sharp contrast to that in the N-I-S samples, suggesting significant redistribution of quasiparticles in F-I-S due to the longer lifetime of spin-polarized quasiparticles. Application of conventional theory for nonequilibrium superconductivity to these data further reveal that a substantial chemical potential shift * in F-I-S samples must be invoked to account for the experimental observation, whereas no discernible chemical potential shift exists in the N-I-S samples, suggesting strong effects of spin-polarized quasiparticles on cuprate superconductivity. The characteristic times estimated from our studies are suggestive of anisotropic spin relaxation processes, possibly with spin-orbit interaction dominating the c-axis spin transport and exchange interaction prevailing within the CuO 2 planes. Several alternative scenarios attempted to account for the suppression of critical currents in F-I-S samples are also critically examined, and are found to be neither compatible with experimental data nor with the established theory of nonequilibrium superconductivity.

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Nonequilibrium superconductivity

Cited by 110 publications

References 33 publications

Theory of parametrically amplified electron-phonon superconductivity

Theory of parametrically amplified electron-phonon superconductivity

Analysis of the phonon spectrum emitted by superconducting Al-tunneling junctions at high quasiparticle injection rates

Spin-polarized quasiparticle transport in cuprate superconductors

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