  A novel way to realize a pi Josephson junction is proposed, based on a weak
link in an unconventional d-wave superconductor with appropriately chosen
boundary geometry. The critical current of such a junction is calculated from a
fully selfconsistent solution of microscopic Eilenberger theory of
superconductivity. The results clearly show, that a transition to a pi
Josephson junction occurs for both low temperatures and small sizes of the
geometry.

Superconductivity