Electrical resistivity change due to high-energy X-ray irradiation of oxygen-deficient EuBaCuO

Ishikawa, Norito   ; Chimi, Yasuhiro; Michikami, Osamu*; Iwase, Akihiro*

High-energy X-ray was irradiated to EuBaCuO, which is one of the REBaCuOy (RE=rare earth) compounds, at low temperature (100 K), and the electrical resistivity was measured in situ at the same temperature (100 K). The X-ray energy was chosen near Cu K-edge (9.0 keV), Eu L3-edge (7.0 keV) and Ba L3-edge (5.2 keV) so that the effect of inner-shell excitation can be detected, if any. The irradiation-induced increase in the electrical resistivity is observed during the irradiations with X-ray in the energy range of 5-9 keV. The electrical resistivity monotonically increases as increasing photon dose. Even if the X-ray is switched off, the irradiation-induced effect remains unchanged. The observed effect has an opposite trend compared with that observed for the visible light irradiation which causes persistent photoconductivity. It is also found that the irradiation-induced increase in resistivity scales with the energy absorbed by EuBaCuO.