Photoinduced changes of the in-plane and out-of-plane electronic properties in YBa2Cu3Ox

We report on the photoinduced changes of the electronic properties of YBa2C u3Ox (x approximate to 6.6) thin films, focussing on the electrical anisotr opy in the normal and the superconducting state. The latter was determined from magnetoconductivity measurements, performed before and after light exc itation. and fitting the experimental results to the Aslamazov-Larkin theor y of superconducting order-parameter fluctuations. The normal-state anisotr opy sigma (ab)/sigma (c) was calculated from resistance measurements carrie d out on samples grown on vicinal substrates. We observed that the photodop ing process enhanced superconducting coherence lengths xi (c)(0) and xi (ab )(0), but reduced the superconducting anisotropy xi (ab)(0)xi (c),(0) at al l studied temperatures. In contrast, sigma (ab)/sigma (c) was enhanced by p hotodoping at low temperatures, but reduced at high temperature. Our result s strongly suggest that two different mechanisms contribute to the photodop ing process, with one affecting only the normal-state properties.