Mossbauer Studies On Superconducting La1.82ca1.18(Cu0.99fe0.01)2o6

Mossbauer spectroscopy was used to study the superconducting oxide La1.82Ca1.18(Cu0.99 Fe-57(0.01))2O6 prepared under oxygen pressures of 2 atm (non-superconducting), 50 atm (T(c) = 9 K) and 400 atm (T(c) = 43 K). The spectra recorded at room temperature were paramagnetic. Iron atoms occupy mainly regular copper sites with pyramidal oxygen coordination. The measurements at 4.2 K showed that the samples prepared in 2 and 50 atm are magnetically ordered and suggested that the magnetization direction is parallel to the a, b-plane. In contrast, the magnetic ordering was largely suppressed at 4.2 K in the superconducting sample prepared in 400 atm oxygen.