Realization of high-T_c dc π-SQUIDs

Exploiting the dx2-y2-dominated symmetry of the high-Tc cuprates, we have fabricated thin film dc-π-SQUIDs which consist of high-Tc superconductors only. The characteristics of the π-SQUIDs are compared with the properties of standard high-Tc SQUIDs. Further we show that in superconductors the admixture of various symmetry components of the order parameter does not have to be constant, but in general is characterized by spatial variations. © 2000 Elsevier Science B.V. All rights reserved.