A method. The method includes providing Au-doped Co nanoparticles. The nanoparticles include a combination of non-ferromagnetic nanoparticles and weakly ferromagnetic nanoparticles. The nanoparticles each have an exterior surface. The surfaces of the nanoparticles are functionalized with 7-(5-uracil-ylcarbamoyl)heptanoic acid. A polymer is provided having a general formula including a uracil group. A dispersion is formed by agitating a solution of the nanoparticles. The solution is spin cast into a film. The film is heated under vacuum at a first temperature, TFM, resulting in inducing ferromagnetism in the non-ferromagnetic nanoparticles and converting the non-ferromagnetic nanoparticles to ferromagnetic nanoparticles, and resulting in enhancing ferromagnetism in the weakly ferromagnetic nanoparticles. The nanoparticles are aligned such that magnetic easy axes of the nanoparticles are oriented by applying a magnetic field to the dispersion while at a second temperature less than TFM. The axes align in a plane parallel to a plane of the film.