Modulation of the magnetoimpedance effect of ZnO:Ag/NiFe heterostructures by thermal annealing

Abstract

The magnetization dynamics in ZnO:Ag/NiFe heterostructures has been investigated through magnetoimpedance measurements. By annealing the ZnO:Ag layer during the production process of the samples, structural and magnetic features of the whole heterostructure are modified, showing that the dynamical magnetic response of the heterostructure is strongly dependent on the annealing temperature. The magnetoimpedance results are discussed in terms of the different mechanisms governing the magnetization dynamics at distinct frequency ranges and in terms of the evolution of the ZnO:Ag layer with annealing. The presented results open new roads for technological application of semiconductor/ferromagnetic heterostructures.

Improving the Room-Temperature Ferromagnetism in ZnO and Low-Doped ZnO:Ag Films Using GLAD Sputtering

“…The depositions were performed through a metallic zinc target with at.% purity and dimensions of cm connected to a DC source. To produce the doped ZnO:Ag films, the Zn target was decorated with a specific amount of Ag pellets, symmetrically distributed along the main erosion area (50 cm ), in order to set the silver concentration at 2 wt.% and 4 wt.% [ 30 , 37 ]. In particular, the zigzag-like columnar structure was obtained by rotating the substrate in relation to the plasma particle flux ( ) using the so-called tangent and cosine rules [ 38 , 39 , 40 ].…”

Influence of Core-Wire on Giant Magnetoimpedance Effect in Electrodeposited Composite Wires

“…These studies not only provided physical understanding of GMI phenomenon 1 but also assisted in designing low field magnetic sensors. 2,3 Quite often a soft magnetic element of few micrometres diameter is used in these sensors. There have been several attempts to improve the field sensitivity of the element by choosing magnetic materials in different geometrical shapes, such as, magnetic ribbons, 4 wires, 5 thin films, 6 multilayers.…”

“…7 The GMI effect has been observed in composite wires that consist of a highly conductive non-magnetic inner core and soft magnetic shell. 2,5 Experimental and theoretical studies have demonstrated that the presence of highly conductive inner core in composite wires aids in improving GMI effect. 3,[8][9][10][11][12] Owing to their nearly zero magnetostrictive property Permalloy films with composition close to Ni 80 Fe 20 , have been extensively investigated in various geometries.…”