Contributions to photodoping in oxygen-deficient YBa₂Cu₃O_x films

Autor(en)

C. Stockinger, W. Markowitsch, W. Lang, W. Kula, R. Sobolewski

Abstrakt

We report our studies on the superconducting and normal-state properties of metallic YBa/sub 2/Cu/sub 3/O/sub x/ thin films (T/sub c,mid/ approximately= 52 K) exposed to long-term white-light illumination (photodoping). It was observed that the effects of photoexcitation strongly depended on the temperature at which the photodoping was performed. At low temperatures, both the Hall mobility and the Hall number were photoenhanced, whereas, at temperatures slightly below room temperature, the Hall mobility initially showed an abrupt increase followed by a long-term decrease, and the Hall number increased even stronger than at low temperatures. The enhancement of the film's superconducting transition temperature T/sub c/, caused by photodoping, exhibited the same temperature dependence as the enhancement of the Hall number, being largest ( Delta T/sub c/ approximately=2.6 K) at high temperatures. From the asynchronous behavior of the Hall quantities, we conclude that both the photoassisted oxygen ordering and charge transfer mechanisms contribute to photodoping. The relative contributions of both mechanisms and, thus, the electronic properties of the photoexcited state are strongly temperature dependent. Studies of the relaxation of the photoexcited state at 290 K showed an unexpectedly short relaxation time of the Hall mobility after termination of the illumination. The relaxation saturated somewhat below the initial, undoped value, similarly to the decrease of the Hall mobility,observed upon long illumination. These latter findings give evidence for a competition between the oxygen ordering and thermal disordering processes during and after the photoexcitation in the high-temperature range.

Organisation(en)

Elektronische Materialeigenschaften

Journal

European Physical Journal B

Band

2

Seiten

301-311

Anzahl der Seiten

11

ISSN

1434-6028

DOI

https://doi.org/10.1007/s100510050253

Publikationsdatum

1998

Peer-reviewed

Ja

ÖFOS 2012

103018 Materialphysik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/0075fa1e-ca9e-4fc9-8674-a09d20151d53