Bulk Nature of High-Tc Superconductivity in ErBa2Cu3O6+x

The magnetic response of ErBa2Cu3O6+x has been studied in terms of complex susceptibility χ=χ'-iχ''. Our previous work suggested that the superconductivity of ErBa2Cu3O6+x consists of bulk and weakly-coupled phases. We pulverized the pellet to depress the superconductive couplings in the specimen. The ac susceptibility data well reflect a bulk superconductive nature: χ' is insensitive to the field amplitude and χ'' does not show any change in the transition region, giving sound confirmation of our previous explanation.