Clusters of Long- $c$ Lattice Phase in ${\rm SmBa}_{2}{\rm Cu}_{3}{\rm O}_{y}$ Films Grown in

Phase stability diagram and boundary of a- and c-axis orientation of SmBa₂Cu₃O_y films grown by pulsed laser deposition were studied. In the study, anomalously long-c tetragonal SmBa₂Cu₃O_y were discovered in films grown in low oxygen pressure. The long-c phase has 1% longer c-axis lattice constant compared to normal-c orthorhombic SmBa₂Cu₃O_y and has lower superconducting transition temperature ( ~ 70 K). The long-c phase is able to coexist in the normal-c matrix over a range of oxygen pressure and growth temperature.