Cation ordering within the perovskite block of a six-layer Ruddlesden-Popper oxide from layer-by-layer growth – artificial interfaces in complex unit cells

Abstract

The (AO)(ABO₃)_n Ruddlesden-Popper structure is an archetypal complex oxide consisting of two distinct structural units, an (AO) rock salt layer separating an n-octahedra thick perovskite block. Conventional high-temperature oxide synthesis methods cannot access members with n > 3, but low-temperature layer-by-layer thin film methods allow the preparation of materials with thicker perovskite blocks, exploiting high surface mobility and lattice matching with the substrate. This paper describes the growth of an n = 6 member CaO[(CSMO)₂(LCMO)₂ (CSMO)₂] in which the six unit cell perovskite block is sub-divided into two central La_0.67Ca_0.33MnO₃ (LCMO) and two terminal Ca_0.85Sm_0.15MnO₃ (CSMO) layers to allow stabilization of the rock salt layer and variation of the transition metal charge.