STRUCTURE AND MAGNETIC-PROPERTIES OF QUASI-ONE-DIMENSIONAL COBALT-DOPED SCANDIUM CUPRATE COMPOUNDS

Structure and magnetic properties of the Sc2Cu2-x CoxO5 system were in vestigated up to the solid solution limits x=0.4 and x=0.6. Undoped Sc 2Cu2O5 has, like isostructural Y2Cu2O5, a magnetic structure with weak ferromagnetic coupling along the b-axis and strongly coupled Cu2+ cha ins parallel to the a-axis which were antiferromagnetically coupled be low the Neel temperature of 16 K. Doping with Co2+ caused the paramagn etic Curie temperature (theta(p)) to decrease from the x=0 value of 40 K, making (theta(p)) negative for x>0.2, and caused the Neel temperat ure to increase to about 35 K for x=0.4. Thus the interchain weak ferr omagnetic coupling along the b-axis was weakened and the interchain an tiferromagnetic coupling was strengthened, while the intrachain strong ferromagnetic coupling, which displays the one-dimensional spin-spin interaction, was not influenced by the Co doping. Room-temperature str ucture refinement for Sc2Cu1.6Co0.4O5 from neutron powder diffraction data indicated that random substitution of Co2+ for Cu2+ occurred and that the Cu-O-O-Cu interchain superexchange pathway was enhanced by ge ometric changes as x increased from x=0 to 0.4.