Time-resolved optical response of all-oxide YBa 2 Cu 3 O 7 /La<mml:math xmlns:mml="http://www.w3.org…
2013; American Physical Society; Volume: 87; Issue: 13 Linguagem: Inglês
10.1103/physrevb.87.134514
ISSN1550-235X
AutoresL. Parlato, Riccardo Arpaia, C. de Lisio, F. Miletto Granozio, Giovanni Piero Pepe, Paolo Perna, Vito Pagliarulo, C. Bonavolontà, M. Radović, Y. Wang, Roman Sobolewski, U. Scotti di Uccio,
Tópico(s)Advanced Condensed Matter Physics
ResumoWe present femtosecond pump--probe spectroscopy studies of time-resolved optical reflectivity of all-oxide YBa${}_{2}$Cu${}_{3}$O${}_{7}$/La${}_{0.7}$Sr${}_{0.3}$MnO${}_{3}$ (YBCO/LSMO) superconductor/ferromagnet (S/F) bilayers consisting of a 100-nm-thick YBCO base layer and either 10 or 35 nm LSMO cap thickness. At temperatures far below the YBCO superconducting transition ${T}_{C}$, samples with a 10 nm F overlayer show a photoresponse that is similar to, but faster than, pure-YBCO, 100-nm-thick reference samples, while close to ${T}_{C}$ and above (up to \ensuremath{\sim}160 K) we observe a signature of both the electronic and spin response that cannot be interpreted as an incoherent sum of contributions from the two layers. The photoresponse of the S/F structures with the 35-nm LSMO layer always qualitatively follows that of the pure LSMO, but with a shorter relaxation time. In all cases, the YBCO/LSMO nonequilibrium dynamics can be modeled using a generalized multitemperature model, which is a superposition of the dynamics of the three-temperature models that are used to describe the superconductor and ferromagnet subsystems, respectively. The long term of the photoresponse signal of the S/F bilayer can be well fitted with the two characteristic relaxation times.
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