Ferromagnetic phase transition and single-gap type electrical conductivity of epitaxial LaMnO3/LaAlO3 superlattices

High-quality epitaxial LaMnO3/LaAlO3 superlattices (SLs) with (0 0 1), (0 1 1), and (1 1 1) out-of-plane orientation were grown by pulsed laser deposition. This SL material was predicted theoretically as a Chern insulator for realizing the quantum anomalous Hall effect. In our investigations, a paramagnetic-ferromagnetic phase transition is found with decreasing temperature around 100 K, indicating a controllable ferroic order at low temperatures. Electrical transport measurements reveal a thermally activated single-gap behavior with a fitted band gap of 436 meV for the (1 1 1)-oriented SL. With that, the results prove the predictions of a ferromagnetic background in the SLs, and of a gapped band structure.