High Performance Magnetoimpedance in FeNi/Ti Nanostructured Multilayers with Opened Magnetic Flux

Abstract

Magnetic [FeNi (170 nm)/Ti (6 nm)]3/Cu (L(cu) = 250 or 500 nm)/[Ti (6 nm)/FeNi (170 nm)]3 multilayers were designed with focus on high frequency applications. They were deposited onto glass or a microfluidic system compatible flexible Ciclo Olefin Copolymer substrate and comparatively tested. A maximum sensitivity for the total impedance of 110%/Oe was obtained for a driving current frequency of 30 MHz for [FeNi/Ti]3/Cu (L(cu) = 500 nm)/[Ti/FeNi]3 multilayers deposited onto a glass substrate and 45%/Oe for a driving current frequency of 65 MHz for the same multilayers deposited onto the flexible polymer substrate, a very promising result for applications. The possibility of using flexible substrate/[FeNi/Ti],/Cu/[Ti/FeNi]3 multilayers as MI pressure-sensitive elements was also demonstrated.

Handling magnetic anisotropy and magnetoimpedance effect in flexible multilayers under external stress

“…Regarding to MI in flexible multilayers, in the recent past, distinct groups have reported very interesting results [15][16][17][18][19][20], opening the possibilities for the use of flexible substrates in the development of MI based sensors devices for field detection. In particular, our group has shown that non-magnetostrictive NiFe/(Ag,Ta) multilayers with similar magnetic properties and dynamic magnetic response can be obtained in distinct substrates [15].…”

Sensor Applications of Soft Magnetic Materials Based on Magneto-Impedance, Magneto-Elastic Resonance and Magneto-Electricity

“…In the 50 nm and 25 nm thick films the magnetic domains with in-plane orientation of the magnetization are separated by Néel walls with cross-ties. The different type of domain wall may surely influence the interaction between layers, as discussed in [31] for the case of bilayers. The advantages of weak interlayer interactions for maintaining a good magnetic softness are evident for certain thicknesses of the non-magnetic spacer.…”

“…, matching the thickness of the central Cu layer, as it seems to be the best geometrical configuration leading to the highest MI results [17,31]. …”

Angular Dependence of the Ferromagnetic Resonance Parameters of [Ti/FeNi]6/Ti/Cu/Ti/[FeNi/Ti]6 Nanostructured Multilayered Elements in the Wide Frequency Range

“…There are two microwave phenomenon most studied for soft ferromagnetic nanostructures in a view of their possible sensor and actuator applications: Ferromagnetic resonance [19,20] and giant magnetoimpedance effect [12,13,[21][22][23][24]. Ferromagnetic resonance (FMR) can be defined as resonant absorption of microwave radiation by magnetic material with strongly coupled electrons under application of a DC magnetic field [20,24]. Giant magnetoimpedance effect (GMI) is a change of the total impedance, Z, under application of a moderate external DC field when alternating current of high frequency flows through the ferromagnetic conductor:…”

“…In the experiments described in reference [29] the longitudinal GMI configuration was employed, i.e., DC external field H was parallel to the direction of AC current. In such geometry, the linear polarization of high frequency magnetic field h corresponds to resonant configuration and h is perpendicular to H direction [24,28]. The advantage of prediction and understanding of GMI behavior of nanoscale multilayers in low applied magnetic fields on the basis of FMR data can be widely used for the design of low field planar detectors with nanostructured magnetic components [30].…”