Diamagnetic coupling for magnetic tuning in nano-thin films

Combining nanoscale thin films of magnetic and non-magnetic phases in various hetero-structures has generated a rich variety of new magnetic and magneto-transport phenomena and applications. Here, we propose a coupling between ferromagnetic and diamagnetic layers. We used this diamagnetic coupling to improve the exchange bias field of a diamagnet/ferromagnet/anti-ferromagnet hetero-structure by up to 212%, as evidenced in the experiments presented here. Since diamagnets have very special properties, including temperature independent negative magnetic susceptibilities, this coupling could be a powerful tool in future synthesis of solid state nanostructures such as exchange bias systems, spintronic devices, magnetic random access memories, sensors, and multiferroics

Study of roughness effect in Fe and Co thin films prepared by plasma magnetron sputtering

We report the experimental and theoretical study of a substrate roughness surface induced magnetic anisotropy in thin films of Fe and Co. The experimental results confirm previously reported data on NiFe thin films and indicate that rough substrates increase the magnetic coercive fields in magnetic thin films. This effect is most prominent in films of thickness comparable to the surface roughness values and materials of small volume magnetic anisotropy. We determined the coercive field of 15 nm Fe thin film sample deposited onto rough PVDF to be 256 Oe, which is more than doubled the value of the coercive field of 15 nm Fe films coated under identical conditions, onto smooth Si substrates. The effect is visible for Co films but weaken by its increased volume magneto-crystalline anisotropy. These results are important for applications based on magnetic thin film where the magnetic properties could be adjusted via substrate roughness engineering