Quasiparticle relaxation dynamics in cuprates and lifetimes of low-energy states: Femtosecond data from underdoped to overdoped YBCO and mercury compounds

Abstract

We show that low-energy spectral features in the cuprates can be separated into different components by the measurement of the recombination dynamics of different low-energy excitations in real-time using femtosecond laser spectroscopy. Quasiparticle (QP) recombination across the gap and intra-gap localized state relaxation processes exhibit qualitatively different time- and temperature-dependences. The relaxation measurements also show the existence of two distinct coexisting energy gaps near optimum doping and in the overdoped region, one more or less temperature independent (which exists above and below Tc) and one which closes at Tc in a mean-field like fashion. Thus systematic studies of QP recombination as a function of doping and temperature suggest that the ground state of the cuprates is a mixed Boson-Fermion system with localised states present over the entire region of the phase diagram.

arXiv comment4 pages, acepted for publication in Physica C, invited paper given at M2S, Feb. 20 - 25, 2000, Houston, USA

References in corpus (9)

• Quasiparticle relaxation dynamics in superconductors with different gap structures: theory and experiments on YBa_{2}Cu_{3}O_{7-δ}
• The superconducting gap Δ_{c}, the pseudogap Δ_{p} and pair fluctuations above Tc in overdoped YCaBaCuO from femtosecond time-domain spectroscopy
• Single particle and collective excitations in the one-dimensional charge density wave solid K0.3MoO3 probed in real time by femtosecond spectroscopy
• Distinct charge and spin gaps in underdoped YBa2Cu3O7-x
• Carrier relaxation dynamics in intra-gap states: the case of the superconductor Y Ba_2 Cu_3O_7-delta and the charge-density-wave semiconductor K_0.3MoO_3
• Non-equilibrium Superconductivity and Quasiparticle Dynamics studied by Photo Induced Activation of Mm-Wave Absorption (PIAMA)
• A study of photoexcited carrier relaxation in YBa_2Cu_3O_(7-d) by picosecond resonant Raman spectroscopy
• Evidence for crossover from a Bose-Einstein condensate to a BCS-like superconductor with doping in YBa2Cu3O(7-x) from quasiparticle relaxation dynamics experiments
• The enhancement of the localization length for two interacting particles is vanishingly small in transfer-matrix calculations

Cited by in corpus (1)

• Clocking the Onset of Bilayer Coherence in a High-${\mathrm{T}}_{\mathrm{C}}$ Cuprate