Magnetic properties of (Bi, Pb)(2)(Sr, La)(2)(Ln, La)(2)Cu2Oz (Ln = Sm, Eu, Gd, Dy)

SQUID and ESR measurements were performed for (Bi, Pb)(2)(Sr, La)(2)(Ln, La )(2)Cu2O= (Ln = Sm, Eu, Gd, Dy) heat-treated under a high pressure of oxyge n, and their magnetic properties were investigated. A weak diamagnetic magn etization due to superconductivity was observed in a temperature range belo w 44 - 46 K, and its magnetic susceptibility was determined as - (1.2 simil ar to 2.0) x 10(-4) at 5 K under the static magnetic field of 5 kOe. Furthe r, a weak or short-range antiferromagnetic order was observed even at room temperature in paramagnetic (Bi, Pb)(2)(Sr, La)(2)(Gd, La)(2)Cu2O=, and its temperature variation was investigated. The exchange field between Gd3+ sp ins was concluded to be larger than 3 kOe at room temperature. (C) 1993 Els evier Science B.V. All rights reserved.