Ultrafast carrier relaxation dynamics in single-layer cuprates

Schneider, Michael L.; Demšar, Jure; Glinka, Yuri D.; Klimov, A. V.; Krapf, A.; Rast, S.; Ren, Yuhang; Si, Weidong; Xu, Ying; Zeng, Xianghui; Božović, I.; Lüpke, G.; Manzke, R.; Sobolewski, Roman; Taylor, Antoinette; Tolk, N. H.; Xi, X. X.; Joynt, Robert; Onellion, M.

doi:10.1209/epl/i2002-00286-8

Cited by 44 publications

(44 citation statements)

References 28 publications

(75 reference statements)

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“…In addition to superconducting gaps also the presence of a pseudogap was reported by NMR 12,13 and point-contact Andreev spectroscopy 14 in La-1111. Time resolved spectroscopy has been very instrumental in elucidating the nature of the electronic excitations in superconductors, particularly cuprates, by virtue of the fact that different components in the low-energy excitation spectrum could be distinguished by their different lifetimes [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] . Moreover, the relaxation kinetics can give us valuable information on the electronic density of states 16 and electron-phonon coupling 30 .…”

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confidence: 99%

Quasiparticle relaxation dynamics in spin-density-wave and superconductingSmFeAsO1−xFxsingle crystals

et al. 2010

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We investigate the quasiparticle (QP) relaxation and low-energy electronic structure in undoped SmFeAsO and near-optimally doped SmFeAsO0.8F0.2 single crystals-exhibiting spin-density wave (SDW) ordering and superconductivity, respectively-using pump-probe femtosecond spectroscopy. In the undoped single crystals a single relaxation process is observed, showing a remarkable critical slowing down of the QP relaxation dynamics at the SDW transition temperature TSDW125 K. In the superconducting (SC) crystals multiple relaxation processes are present with distinct SC-state quasiparticle recombination dynamics exhibiting a BCS-like T-dependent superconducting gap, and a pseudogap (PG)-like feature with an onset above 180 K indicating the existence of a pseudogap of magnitude 2ΔPG120 meV above Tc. From the pump-photon energy dependence we conclude that the SC state and PG relaxation channels are independent, implying the presence of two separate electronic subsystems. We discuss the data in terms of spatial inhomogeneity and multiband scenarios, finding that the latter is more consistent with the present data.

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Quasiparticle relaxation dynamics in spin-density-wave and superconductingSmFeAsO1−xFxsingle crystals

et al. 2010

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“…Correspondingly, a variety of femtosecond ultrafast probe technique were put forward for investigation of transient relaxation processes in many semiconductors, such as time-resolved linear and secondharmonic reflectivity measurements, pump-probe transmission and reflectivity technique [10,11]. The development of semiconductor devices requires a clear understanding of ultrafast electrons and phonons dynamical process on a picosecond or even a femtosecond time scale.…”

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Ultrafast dynamics of BixSb1-x film studied by femtosecond pump–probe technique

Zhou

Jiang

et al. 2010

Optics Communications

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“…[1][2][3][4][5][6][7][8][9] Recent ARPES and SR reports 10-12 on La 2−x Sr x CuO 4 provide a better understanding of the electronic structure and transport properties that aid in interpreting femtosecond pump-probe measurements. Specifically, for ͑0.02-0.03͒ Ͻ x Ͻ 0.06, the samples are in a spin-glass phase; the band of carriers in the ͗0,͘ direction of the Brillouin zone exhibits a binding energy of ϳ0.2 eV.…”

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confidence: 99%

“…We also note that the data for the x = 0.06 and x = 0.30 samples are consistent with that previously taken in different labs. 7 We are unaware of any femtosecond time resolved data taken on x = 0.02-0.03 samples.…”

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confidence: 99%

“…4,17 However, for metallic cuprates, experiments have shown a more complex behavior which is dependent on the laser fluence used. [5][6][7][8][9] At the lowest fluencies reported ͑9 ϫ 10 −8 J/cm 2 ͒, 6,7 ͑ R ͒ exhibits a power law divergence ϰT −N (T = sample temperature, 2 ഛ N ഛ 3). At higher, but still perturbative fluence ͑ϳ5 ϫ 10 −6 J/cm 2 ͒, the relaxation time of La 2−x Sr x CuO 4 is almost independent of temperature in the metallic state, increases across the superconducting phase transition, and, except near the phase transition temperature, 8 is almost independent of temperature within the superconducting state.…”

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Electron dynamics in metallic and spin-glass cuprates

Schneider

Onellion

et al. 2004

Phys. Rev. B

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Using femtosecond pump-probe measurements, we present transient optical reflectivity measurements of metallic, superconducting and spin-glass La 2−x Sr x CuO 4 cuprates. The rise time is temperature-independent and resolution-limited ͑Ͻ50 fs͒ for metallic sample, and is much faster than spin-glass samples ͑ϳ200 fs͒ at all temperatures. A divergence in the electron-lattice relaxation ͑ R ͒ time with temperature is observed for the metallic samples, but not for spin-glass samples. PACS number(s): 61.66. Ϫf, 61.72.Ff Femtosecond optical pump-probe measurements provide insight on ultrafast carrier dynamics occurring on femtosecond and picosecond time scales. 1-9 Recent ARPES and SR reports 10-12 on La 2−x Sr x CuO 4 provide a better understanding of the electronic structure and transport properties that aid in interpreting femtosecond pump-probe measurements. Specifically, for ͑0.02-0.03͒ Ͻ x Ͻ 0.06, the samples are in a spin-glass phase; the band of carriers in the ͗0,͘ direction of the Brillouin zone exhibits a binding energy of ϳ0.2 eV. However, Ref. 11 reports an important and unexpected result: in the nodal ͑͗ , ͒͘ direction of the Brillouin zone, there is a quasiparticle state with some coherent spectral intensity that disperses through the chemical potential. By contrast, x ജ 0.06 samples have a van Hove singularity, that is, a saddle point in the band dispersion which leads to a divergence in the density of states, near the chemical potential. There is general agreement that the van Hove singularity is near the chemical potential for all metallic cuprates. 11 We measured the dynamics when the carriers near the chemical potential are in the nodal direction ͑0.02Ͻ x Ͻ 0.06͒, and, separately, when most carriers near the chemical potential are in the van Hove singularity ͑x = 0.06-0.30͒. Further, since x = 0.06 samples are superconducting and x = 0.30 samples are not, we can distinguish the effects of the superconducting phase transition. This is, to our knowledge, the first time femtosecond pump-probe methods have been explicitly used to obtain information about carriers in specific parts of the Brillouin zone.Three different sample stoichiometries of 100-nm-thick La 2−x Sr x CuO 4 films were measured, x = 0.02-0.03, x = 0.06, and x = 0.30. The films were epitaxially grown with pulsed laser deposition on SrTiO 3 with a 100 nm SrLaAlO 4 buffer layer between the substrate and the La 2−x Sr x CuO 4 film. 13 All of the samples were cooled, after deposition, in molecular oxygen. A range of 100 nm thin film samples with 0.00ഛ x ഛ 0.30 were grown with the SrLaAlO 4 buffer layer on SrTiO 3 substrates. The T C values for the samples were determined by susceptibility measurements. The superconducting samples exhibited a 10-90% width of less than 2 K. It was found that the samples exhibit a phase diagram similar to that of the bulk material with slightly higher T C values in the films due to the induced strain from the buffer layer and substrate. Further details of sample preparation and characterization are provided in...

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Ultrafast carrier relaxation dynamics in single-layer cuprates

Cited by 44 publications

References 28 publications

Quasiparticle relaxation dynamics in spin-density-wave and superconductingSmFeAsO1−xFxsingle crystals

Quasiparticle relaxation dynamics in spin-density-wave and superconductingSmFeAsO1−xFxsingle crystals

Ultrafast dynamics of BixSb1-x film studied by femtosecond pump–probe technique

Electron dynamics in metallic and spin-glass cuprates

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