Surfaces of the perovskite manganites La1-xCaxMnO3

Angle-resolved core-level photoemission has been utilized to study the surf aces of crystalline thin films of manganite La1-xCaxMnO3 (x = 0.1 and 0.35) . It is found that both the surface termination and Ca surface concentratio n depend on the bulk Ca concentration. For La0.65Ca0.35MnO3, the terminal l ayer is predominately Mn-O, while for La0.9Ca0.1MnO3, the majority of the s urface is La/Ca-O terminated. Both surfaces exhibit a large enhancement in the Ca concentration compared to the bulk with the La0.9Ca0.1MnO3 sample, h aving a larger surface Ca concentration than for the La0.65Ca0.35MnO3 mater ial. [S0163-1829(99)04420-3].