MÖSSBAUER INVESTIGATION OF IRON DOPED YBa2Cu3O7-x

We have recorded 57Fe Mössbauer spectra of YBa2 (Cu1-yFey)3 O7-x powder sample and uniaxially oriented powder for 0.01 ≤ y ≤ 0.1 and x ≈ -0.2 or x ≈ 0.6. In the superconducting x ≈ 0 compounds we see three subspectra for y = 0.01 and four subspectra for y = 0.01. These subspectra correspond to different oxygen configurations around the iron atoms. From the oriented YBa2 (Cu0.94Fe0.06)3 O7.2 and YBa2 (Cu0.9Fe0.1)3 O6.4 compounds we deduce that more than 90 % iron substitutes Cu(1) site. The iron magnetic moments order antiferromagnetically at ≈ 18 K and ≈ 1.5 K for the x = -0.2, y = 0.06 and x = 0, y = 0.01 compounds respectively