superlattices

Rare earth nickelates (RNiO₃ (RNO), R = rare earth) stand out for their unique metal to insulator transition (MIT) upon reducing temperature (T_MI), accompanied by an unusual antiferromagnetic ordering at T_Néel≤T_MI. In bulk, NdNiO₃ (NNO) exhibits T_Néel=T_MI, whereas SmNiO₃ (SNO) displays T_Néel<T_MI. It has been shown that the T_MI and T_Néel of the corresponding films can be tuned over a wide temperature range by means of epitaxial strain. Moreover, by growing along the (111)_pc crystallographic direction, one can induce splitting of T_MI and T_Néel over a temperature range never achieved for films grown in the (001)_pc-orientation [1] . Here, we adopt a new strategy to study the interfacial matching constraints in RNiO₃-based heterostructures and their impact on the electronic properties by growing (001)_pc and (111)_pc-oriented (m(SNO)/n(NNO))_N superlattices (SLs). We have found that the T_MI and T_Néel of the whole system depend on the superlattice wavelength (Λ=m+n) with a single T_MI for the shortest superlattice period (Λ). In order to understand the evolution of the lattice distortions with the SL periodicities and how interfacial coupling affects T_MI and T_Néel, theoretical predictions will be shown.
[1] Catalano et al., APL Materials 3, 062506. (2015)