Functional Magnetic Micro- and Nanowires: From Microstructure Tailoring to Advanced Sensing Applications
Magnetic amorphous and nanocrystalline wires and micro/nanowires obtained by rapid quenching from the melt show specific magnetic characteristics determined by (1) their disordered or partially disordered structures and (2) their cylindrical symmetry which causes the formation of magnetic domain structures extremely favorable to various applications, like sensors, switching devices, magnetic cores, spintronic devices, or devices based on domain wall logic. A comprehensive understanding of the dependence of the magnetic and magnetoelastic properties of Fe, Co and (Co,Fe)-rich microwires on different external factors (applied magnetic field, force, and torque) would significantly facilitate the take-up of these materials as sensing elements in various types of sensors for electronics, automotive, aeronautics, retail industry or medicine. The various magnetic anisotropies in different types of wires also play an important role in defining the value of the exchange length in each case, i.e., the distance below which the nanosized grains will be exchange-coupled. All these aspects will be discussed in detail considering the specific microstructure, the magnetic domains, and the annealing conditions.