Ferromagnetism in LaFeO/LaNiO superlattices with high Curie temperature.

Interfacing complex oxides in atomically engineered layered structures can give rise to a wealth of exceptional electronic and magnetic properties that surpass those of the individual building blocks. Herein, we demonstrate a ferromagnetic spin order with a high Curie temperature of 608 K in superlattices consisting of otherwise paramagnetic perovskite LaNiO (LNO) and antiferromagnetic LaFeO (LFO). The ferromagnetism likely results from the covalent exchange due to interfacial charge transfer from Fe to Ni cations. By deliberately controlling the thickness of the LNO sublayers thus the amount of charge transfer, a robust ferromagnetism of 4 u is realized for a stacking periodicity consisting of one single unit cell of both LNO and LFO, an emergent double perovskite phase of LaFeNiO with B-site layered ordering configurations. The ferromagnetic LFO/LNO superlattices offer great potential for the search of emergent magnetodielectric and/or multiferroic properties as well as applications in spintronics and electrocatalysts.