LOW TEMPERATURE MAGNETIC ORDER AND THE INSULATOR TO METAL TRANSITION IN THE Y1-xCaxBa2[Cu0.99257Fe0.008]3O6.1 SYSTEM STUDIED BY MÖSSBAUER SPECTROSCOPY

Deoxygenated Y1-xCaxBa2[Cu0.99257Fe0.008]3O6.1 compounds with calcium content of x=0.05, 0.08, 0.12, 0.16, 0.2, 0.26 were prepared by the standard ceramic method. The system exhibit insulator to metal transition. The onset of superconductivity is detected in the sample with x=0.26. The influence of doped holes on low temperature antiferromagnetic order has been investigated. Low temperature Mossbauer spectra consist of two sextets with relative ratio changing with hole concentration. The sextets are broadened, their shape and temperature dependence indicate the existence of magnetic order fluctuations with the relaxation time slightly higher than the observation time of the method ~10-7s.