3D magnetic nanowire networks

In this chapter, we report on the significance of a template-assisted synthesis of complex nanowire-based architectures with an excellent control over geometrical features and morphology for obtaining tunable magnetic, magneto-transport, and thermoelectric properties. The interplay between the structural, magnetic, and magneto-transport properties of three-dimensional (3D) nanowire networks made of various magnetic metals and alloys was investigated. The ease of carrying out magneto-transport measurements and the feasibility to obtain large anisotropic magneto-resistance signals, being stable overtime, for example, in CoNi nanowire networks made them very interesting structures for their use as magnetic sensors. Also, the template-assisted method opens up the possibility for the fabrication of 3D magnetic nanotube networks with precise spatial arrangement and diameter and wall thickness of 10–100 nm controlled individually. Finally, embedded nanowire networks in porous polymer films are also perspective materials for spin caloritronics applications. The fabrication of centimeter-scale interconnected network films made of multilayered nanowires showing giant magneto-resistance and giant magneto-thermoelectric effects are demonstrated. Our investigation reveals the possibility of performing efficient magnetic control of heat flux for thermal management of electronic devices and constitutes a simple and cost-effective pathway for fabrication of large-scale flexible, light weight, and shapeable thermoelectric coolers exploiting the spin degree of freedom. Besides, our flexible thermoelectric films based on macroscopic 3D interconnected nanowire networks can also be used in applications for devices with low energy requirements when the supply of heat essentially is free as with waste heat