Femtosecond spectroscopy has been used to investigate the quasiparticle relaxation times in a nearly optimally doped chalcogenide superconducting FeSe0.5Te0.5 thin film. It is characterized by an enhancement of the critical temperature Tc = 19.1 K by strain. Experimental results indicate the existence of a temperature dependence of the quasiparticle recombination time τR in the superconducting state where an energy gap Δ(T) is present. A fitting procedure based on a BCS-like assumption for τR gives Δ0 = 4.1 ± 0.4 meV for the superconducting energy gap extrapolated at T = 0, which corresponds to 2Δ0/kBTc = 4.9 ± 0.5. Accordingly, an estimation of the characteristic phonon energy and the electron-phonon coupling constant λ is reported and discussed. The obtained value λ ≈ 0.6 is in good agreement with other similar determinations obtained by different techniques and numerical approaches. The small value of λ confirms that a phonon-mediated coupling cannot be the only mechanism leading to the formation of the superconducting state in FeSeTe films.
Ultrafast quasiparticle relaxation dynamics in high quality epitaxial FeSe0.5Te0.5thin films / C., Bonavolont?; Parlato, Loredana; Pepe, GIOVANNI PIERO; DE LISIO, Corrado; M., Valentino; E., Bellingeri; I., Pallecchi; M., Putti; C., Ferdeghini. - In: SUPERCONDUCTOR SCIENCE & TECHNOLOGY. - ISSN 0953-2048. - STAMPA. - 26:(2013), pp. 075018-075022. [10.1088/0953-2048/26/7/075018]
Ultrafast quasiparticle relaxation dynamics in high quality epitaxial FeSe0.5Te0.5thin films
PARLATO, LOREDANA;PEPE, GIOVANNI PIERO;DE LISIO, CORRADO;
2013
Abstract
Femtosecond spectroscopy has been used to investigate the quasiparticle relaxation times in a nearly optimally doped chalcogenide superconducting FeSe0.5Te0.5 thin film. It is characterized by an enhancement of the critical temperature Tc = 19.1 K by strain. Experimental results indicate the existence of a temperature dependence of the quasiparticle recombination time τR in the superconducting state where an energy gap Δ(T) is present. A fitting procedure based on a BCS-like assumption for τR gives Δ0 = 4.1 ± 0.4 meV for the superconducting energy gap extrapolated at T = 0, which corresponds to 2Δ0/kBTc = 4.9 ± 0.5. Accordingly, an estimation of the characteristic phonon energy and the electron-phonon coupling constant λ is reported and discussed. The obtained value λ ≈ 0.6 is in good agreement with other similar determinations obtained by different techniques and numerical approaches. The small value of λ confirms that a phonon-mediated coupling cannot be the only mechanism leading to the formation of the superconducting state in FeSeTe films.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
