Magnetic properties of Bi-doped Gd2-xBixCuO4 cuprates

Structural and magnetic properties of the new Bi-doped Gd2-xBixCuO4 system are reported. With the doping of larger trivalent Bi3+ ions, the T' phase s olubility region is retained in the range of 0 less than or equal to x less than or equal to 0.1. Weak ferromagnetic or canted antiferromagnetic order ing temperature T-N(Cu) of Cu moments decreases from 282 K for Gd2CuO4 to 2 58 K for Gd1.93Bi0.07CuO4 and 256 K for Gd1.9Bi0.1CuO4. Due to small intern al field Hint associated with weak ferromagnetic order, the spin reorientat ion temperature T-sr(Cu) is field dependent and decreases from 24 K in 1 G to 12 K in 1 kG for Gd1.95Bi0.05CuO4. Preliminary powder x-ray Rietveld ref inement analysis using the T' phase ideal oxygen position indicates a large temperature factor B for the oxygen sites in the Cu-O plane and suggests t hat the degree of oxygen structural distortion may be closely related to th e strength of weak ferromagnetic order. (C) 1999 American Institute of Phys ics. [S0021-8979(99)15608-1].