TERRACE GROWTH IN PARTIALLY MELT-REGROWN EUBA2CU3O7-DELTA HIGH-T-C SUPERCONDUCTORS

An SEM and STM study was made of terrace formation in partial melt-reg rown EuBa2Cu3O7-delta Terraces form above 920 degrees C, well below th e bulk melting temperature (1075 +/- 10 degrees C). The terrace format ion is accompanied by significant grain growth, possibly triggered by a ''surface-melting'' transition. Melting occurs in a layer a few mono layers thick, and the highly mobile layers reconstruct into terraced f orm due to a faceting transition. The terrace growth can be reproduced by a theoretical faceting model. The STM also reveals a finer-scale s inusoidal modulation of the surface, of unknown origin.