Electronic behavior of spatially distributed junction small inductance dc p-SQUIDs Boris Chesca * ,1 , Reinhold Kleiner Experimentalphysik II, Physikalisches Institut, Universit atT ubingen, Auf der Morgenstelle 14, D-72076 T ubingen, Germany Received 17 April 2000; received in revised form 3 July 2000; accepted 4 July 2000 Abstract As investigated theoretically [Annalen der Physik Leipzig) 8 1999) 511; Phys. B, in press] spatially distributed junction small inductance dc p-SQUIDs exhibit unusual electric transport properties in both zero-voltage and voltage states. The purpose of this paper is to summarize the peculiarities of this electronic behavior in order to a) reveal some of the advantages the device has over other known Josephson junctions based con®gurations when used as a tool to investigate the order parameter symmetry in high-T c superconductors, and b) to emphasize its potential for applica- tions in superconducting electronics. Ó 2001 Elsevier Science B.V. All rights reserved. Keywords: Spatially distributed junctions; SQUID; Electronic transport properties 1. Introduction The spatially distributed junction SDJ) small inductance dc p-SQUID is sketched in Fig. 1. It consists of two junctions J 1 and J 2 of width S 1 and S 2 , respectively, connected in parallel between two superconductors with predominantly d x 2 y 2 -wave symmetry of the order parameter. The two junc- tions with critical currents I 1 and I 2 are separated by a distance D and their interfaces are oriented perpendicular to the respective SQUID arms. In the voltage state the latter condition is essential for the formation of steady electromagnetic waves in the two dielectric cavities formed by the two junctions, and therefore for Fiske steps to occur. Unlike the usual case the SQUID has two SDJ, i.e., in the presence of a magnetic ®eld B applied perpendicular to the SQUID plane, the magnetic ¯ux coupled to the junctions is not negligible and has to be considered. In addition, its inductance is so small that the ¯ux created by a circulating screening current in the SQUID loop is negligible, i.e., b  2LI c =U 0  1. For the SQUID considered, the two c-axis oriented superconductors are mis- aligned under an angle of 45° with respect to each other. Further, the angle between the [0 1 0] axis of superconductor 1 and the interface planes of both junctions see Fig. 1) are chosen to equal a value a. a takes values in the interval 22.5±67.5°) so that in the absence of an applied magnetic ®eld there is a d x 2 y 2 -wave induced p-phase shift between the two junctions and therefore the device operates as a dc p-SQUID. For the special case of a  45°, an Physica C 350 2001) 180±186 www.elsevier.nl/locate/physc * Corresponding author. E-mail address: boris.chesca@physik.uni-augsburg.de B. Chesca). 1 Also at: Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, Universit at Augsburg, D-86135 Augsburg, Germany. 0921-4534/01/$ - see front matter Ó 2001 Elsevier Science B.V. All rights reserved. PII:S0921-453400)01602-6