Proximity Effect and Josephson Coupling in the SO(5) Theory of High-TcSuperconductivity

Abstract

We consider proximity effect coupling in Superconducting/Antiferromagnetic/Superconducting (S-A-S) sandwiches using the recently developed SO(5) effective theory of high temperature superconductivity. We find that, for narrow junctions, the A region acts like a strong superconductor, and that there is a critical junction thickness which depends on the effective SO(5) coupling constants and on the phase difference across the junction, at which the A region undergoes a Freedericksz-like transition to a state which is intermediate between superconductor and antiferromagnet. For thick junctions, the current-phase relation is sinusoidal, as in standard S-N-S and S-I-S junctions, but for thin junctions it shows a sharp break in slope at the Freedericksz point.

Recent developments in the SO(5) theory of high Tc superconductivity

“…Progress towards the final goal is made historically before the first two. The SO(5) quantum rotor model with anisotropic couplings captures the basic physics of the microscopic SO(5) models, but contain phenomenological parameters which may eventually be determined experimentally [6,11]. It is tempting to believe that all models with this type of phase diagram flow to this theory in the long wave length limit [16].…”

“…Since my review in the Proceedings of the International Conference on Materials and Mechanisms of Superconductivity [3], some important progress has been made due to the efforts of many groups [4][5][6][7][8][9][10][11][12]. There has also been the criticisms raised.…”

Proposed Design of a Josephson Diode

“…In strongly correlated electron systems, many other quantum phases exist in the vicinity of the superconducting phase, which give rise to many salient features in Josephson junctions. For example, a long range proximity effect in superconducting-antiferromagneticsuperconducting (SAS) junctions was predicted [1] based on the competition between the superconducting and antiferromagnetic phases in high temperature superconductors [2 -5]. An abrupt change of the Josephson critical current was predicted in the junction arrays near the superconductor -Mott-insulating phase transitions [6].…”

“…As a result, the J 3 term describing the recombination and regeneration processes dominates over other terms. The second is that if 2 is set to 0, we recover the conventional form of the Josephson coupling energy, i.e., H J cos 1 . Without the insulating region, the number of singlons is not determined in both sides.…”

“…1 i is the conventional phase of superconducting order parameter, which is the conjugate variable to the density, namely, n i ; 1 …”