Comparative study of LaNiO$_{3}$/LaAlO$_{3}$ heterostructures grown by oxide MBE and PLD techniques*

The physical properties of functional oxides can be altered by, e.g., dimensionality, strain, interfacial interaction and doping. Ozone assisted molecular beam epitaxy (oxide MBE) is a technique that gives wide access to all tuning parameters while having a low deposition energy. We succeeded in growing high-quality heterostructures based on LaNiO$_{3}$ with oxide MBE and pulsed laser deposition (PLD) and compared crystallinity, resistivity, x-ray absorption (XAS), orbital polarization and high-resolution transmission electron microscopy (HRTEM) images. Despite the difference in growth conditions, the samples show essentially the same physical properties: By reducing the layer thickness, LaNiO$_{3}$ turns from a paramagnetic metal into an antiferromagnetic insulator. XAS confirms the nickel $+$III oxidation state and that the orbital polarization is mainly controlled through substrate strain.