Comment on Photoemission study of YBa2Cu3Oy thin films under light illumination

A. HOFFMANN; G. NIEVA; J. GUIMPEL; Y. BRUYNSERAEDE; J. SANTAMARÍA; D. LEDERMAN; IVAN K. SCHULLER

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Lugar: New York; Año: 2006 vol. 97 p. 1197010 - 1197011

0031-9007

In Ref. [1] Asakura et al. suggest that the doping level in YBa2Cu3Oy (YBCO) films grown on Nb-doped SrTiO3 (STO:Nb) substrates is modified due to injection of photoelectrons from the STO:Nb substrate into the YBCO film. However, it is well established that YBCO on its own has intrinsically very pronounced effects due to photoinduced doping changes [2]. The presence of these intrinsic photodoping effects puts into question the role of any photoelectrons from the STO:Nb substrate for the experiments of Asakura et al. Theoretically this implies that the origin of the effect does not reside in the photoelectrons generated in the STO:Nb and the same effect will be observed independently of the choice of substrate.