Magnetism of Ultrathin TiO₂ Films Prepared by Atomic Layer Deposition

High Resolution Image Download MS PowerPoint Slide The discovery of room-temperature ferromagnetism (FM) in pristine TiO 2 films has sparked intense debate regarding its origin, particularly in the absence of conventional magnetic dopants. Herein, for the first time, the FM of ultrathin TiO 2 films grown on LaAlO 3 (LAO) substrates by Atomic Layer Deposition (ALD) is investigated, yielding TiO 2 thicknesses of 1, 5, and 10 nm. The findings reveal a striking thickness-dependent magnetic response, where the 5 nm films exhibit the highest ferromagnetic response, attributed to defect-driven mechanisms. Structural and spectroscopic analyses, complemented by quantum mechanical calculations, highlight the critical role of oxygen vacancies and/or defects, as well as the interface with LAO substrates, in modulating the observed FM. Notably, this work demonstrates that the ferromagnetic behavior is confined to the in-plane direction, reinforcing the role of surface and interface effects. These insights establish that defects play a key role in tuning the electronic and magnetic properties of ultrathin TiO 2 films, paving the way for potential applications in next-generation magnetic devices.