Synthesis and characterization of soft magnetic thin films, nanocomposites, and nanowires by electrodeposition

Electrochemical deposition is an important processing technique for depositing thin films and nanostructures due to its low cost, high yield, low energy requirements, and capability for generating complex and high aspect ratio features. Electrodeposition has been widely used in the microelectronics industry for interconnects, chip packaging, and magnetic storage.; FeCo alloys with composition close to Fe₅₀Co₅₀ have unique magnetic properties including high magnetic moment (24 kG), high permeability, low coercivity, and a Curie temperature of about 1000°C. As a result of these properties, FeCo alloys are utilized in the electrical bearings and transformers of aircraft engines and have recently been considered for applications such as magnetic recording write heads and MEMS devices. High quality FeCo thin films were electrodeposited from sulfamate-based solutions. The influence of various deposition parameters on the composition and properties of FeCo thin films are discussed. The magnetic properties, mechanical properties, and microstructures of these films were also characterized.; The addition of nanometer-sized particles to a host matrix can be used to modify the properties of the matrix, such as mechanical properties and magnetic properties. Nanocomposite Ni/Al₂O₃ and FeCo/TiO ₂ were electrodeposited from a suspension of Al₂O₃ or TiO₂ nanoparticles in aqueous Ni or FeCo electrolytes. The volume fraction of particles incorporated increased with electrode rotation rate and decreased with deposition current density. A kinetic model based on convective diffusion was proposed to illustrate the dependence on deposition parameters of particle codeposition. The composition, microstructure, hardness, and magnetic properties of these nanocomposite films were characterized.; Template-based synthesis was used to fabricate FeCo nanowires with diameters of 20–200 nm. High aspect ratio structures, such as nanowires, allow manipulation of the magnetic shape anisotropy. The structures are of interest for magnetic sensors and magnetic recording. The magnetic coercivity and squareness of FeCo nanowires increased with decreasing wire diameter due to changing in energy barrier for switching magnetization directions. The mass transport process during nanowire deposition will also be discussed.