Co-existence of diamagnetism and ferromagnetism and possible superconductivity in Y8Ba5Zn4O21

In the present study, we investigate structural and magnetic properties of the Y8Ba8Zn4O21 structure, which was recently included in the catalog of the International Centre for Diffraction Data (ICDD) as a prototype structure. It was found that the Y8Ba5Zn4O21 bulk sample seems to be electrically insulating at temperatures of liquid nitrogen and the room temperature. On the other hand, it has quite interesting magnetic properties. Diamagnetic phase transition was observed at similar to 90 K, which resembles that of the superconducting materials. The studied composition repels permanent magnets at the liquid nitrogen temperature. Ferromagnetism also co-exists with diamagnetism in the temperature range between 50 K and 90 K. Possible reasons for these behaviors are discussed. (C) 2010 Elsevier Inc. All rights reserved.