Surfaces of the perovskite manganites La 1-x Ca x MnO 3

摘要: Angle-resolved core-level photoemission has been utilized to study the surfaces of crystalline thin films manganite ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ ($x=0.1$ and 0.35). It is found that both surface termination Ca concentration depend on bulk concentration. For ${\mathrm{La}}_{0.65}{\mathrm{Ca}}_{0.35}{\mathrm{MnO}}_{3},$ terminal layer predominately Mn-O, while for ${\mathrm{La}}_{0.9}{\mathrm{Ca}}_{0.1}{\mathrm{MnO}}_{3},$ majority La/Ca-O terminated. Both exhibit a large enhancement in compared with ${\mathrm{La}}_{0.9}{\mathrm{Ca}}_{0.1}{\mathrm{MnO}}_{3}$ sample, having larger than ${\mathrm{La}}_{0.65}{\mathrm{Ca}}_{0.35}{\mathrm{MnO}}_{3}$ material.