Superconducting EuBa2Cu3O7. A M�ssbauer study

Abstract

EuBa2Cu3O7 shows a sharp transition to zero resistance atT sc =85(1) K. Europium is entirely trivalent. The151Eu Mossbauer recoilless fraction in the range 4–300 K is well-fitted by a Debye model withT sc = 85(1) K. There is no anomaly around 240 K, nor atT sc , and therefore no significant change in the vibrational amplitude of the rare-earth ion. Another sample doped with 1%57Fe, shows two ferric quadrupole doublets associated with Fe3+ on Cu1 and Cu2 sites. There is no sign of any magnetic order down to 4.2 K.