Control of magnetism at the atomic scale

The Giant Magneto-Resistance effect in metallic magnetic multilayer systems forms the basis of highly successful magnetic sensing and storage technology. The active search for new materials that would allow for ever higher sensitivity and controllability is under way. Transition metal oxides (TMO) are particularly attractive, since there is a plethora of isostructural materials with a wide variety of magnetic and electronic properties, which can be seamlessly built into complex heterostructures. In heterostructures composed of different TMO, the disruption introduced even by an ideal interface, can drastically upset the delicate balance of the competing interactions among electronic spins, charges and orbitals, leading to a range of exotic phenomena, including interfacial conduction, magnetism, and superconductivity. Among TMO, Mn-based perovskites AMnO3 (manganites) are one of the best studied classes of materials that exhibit particularly rich set of behaviors tunable by composition, pressure and temperature. It has been recently demonstrated that when put into contact with ferromagnetic (FM) SrRuO3, the interface layer of antiferromagnetic (AF) manganite becomes FM. We have given evidence for manipulating the magnetic properties at the atomic level in digitally synthesized nano-heterostructures. We then engineered interfacial FM in correlated electron materials by means of valence state variation and substrate induced strain.

More details can be read in: Phys. Rev. Lett. 105, 167206 (2010)