FIELD-INDUCED PINNING EFFECT OF ND(BA1-XNDX)(2)CU3O7-DELTA SINGLE-CRYSTAL GROWN BY THE TRAVELING-SOLVENT FLOATING-ZONE METHOD

We have studied the superconducting properties of Nd(Ba1-xNdx)(2)Cu3O7 -delta (Nd123, x approximate to 0.1) single crystals grown by the trav eling-solvent floating-zone method under 0.1% O-2 in Ar atmosphere. Th e enhancement of the magnetization with increasing field is observed i n the hysteresis (M-H) loop in fields both parallel and perpendicular to the c-axis of the Nd123 single crystals as well as in the bulk crys tals prepared by the oxygen-controlled-melt-growth (OCMG) method. The composition variation of Ba/Nd is observed in the matrix of Nd123 crys tals by an analytical TEM equipped with a cold field-emission gun. It turns out that the enhancement is due to the field-induced pinning eff ect ascribed to the weak superconducting Nd-Ba substitution regions in the Nd123 matrix.