Designing global and local magnetic phases with uniaxial lattice expansion

Epitaxy and/or isovalent substitutions are widely used to modify the internal lattice energies that control magnetic phase composition in strongly correlated transition metal oxides (TMO). However, these techniques do not allow for continuous and fine command over structural properties post-growth which hampers our ability to systematically study structure-function relationships. We will present our recent work which relies on low energy helium ion implantation to control uniaxial lattice expansion post-growth to bypass these limitations in epitaxial manganites and nickelates thin films. This strategy is shown to provide a means to control orbital degeneracies which can then be exploited to alter magnetic character of TMOs. Magnetic anisotropy, magnetic ordering type, and magnetic onset temperatures can all be controlled. Further, local application of strain doping allows one to design coexisting magnetic phases of vastly different character into a single crystal wafer.