MAGNETIC ORDER INDUCED BY HYDROGEN IN YBA2CU4O8

Magnetic susceptibility, Mossbauer spectroscopy and x-ray diffraction measurements were performed to study the superconducting (SC) and magn etic properties of hydrogen charged bulk YBa2(Cu0.99Fe0.01)(4)O8Hy. Fo r y<1 the c lattice parameter decreases with y. T-c=59 K is unaffected by hydrogen charging, but the shielding fraction (SF) is reduced shar ply from 38% (at y=0) to 17% and 3% for y=1 and 1.85, respectively. Th e Mossbauer spectra (MS) for hydrogen charged samples contain a magnet ic pattern composed of two sextets, between 4.1 K and T-N=360 K. The r elative amount of the magnetic pattern depends on hydrogen concentrati on. The MS obtained for y=1 is a superposition of spectra obtained for y=0 and those for y=2, showing a phase separation into magnetic and s uperconducting regions in YBa2Cu4O8Hy.