Tuning static and dynamic properties of FeGa/NiFe heterostructures

Abstract

In this work, the frequency-dependent magnetic properties of sputtered Galfenol/Permalloy (Fe85Ga15/Ni81Fe19 or FeGa/NiFe) magnetic multilayers were examined to tailor their magnetic softness, loss at microwave frequencies, permeability, and magnetoelasticity, leveraging the magnetic softness and low loss of NiFe and the high saturation magnetostriction (λs) and magnetization (MS) of FeGa. The total volume of each material and their ratio were kept constant, and the number of alternating layers was increased (with decreasing individual layer thickness) to assess the role of increasing interfaces in these magnetic heterostructures. A systematic change was observed as the number of bilayers or interfaces increases: a seven-bilayer structure results in an 88% reduction in coercivity and a 55% reduction in ferromagnetic resonance linewidth at the X-band compared to a single phase FeGa film, while maintaining a high relative permeability of 700. The magnetostriction was slightly reduced by the addition of NiFe but was still maintained at up to 67% that of single phase FeGa. The tunability of these magnetic heterostructures makes them excellent candidates for RF magnetic applications requiring strong magnetoelastic coupling and low loss.

Static and Dynamic Magnetic Properties of FeGa/FeNi (FeNi/FeGa) Bilayer Structures

“…The linewidth of SA1, SB1, SC1, SA2, SB2, and SC2 is 46.4, 35.8, 36.7, 54.9, 27.81, and 37.26 mT, respectively. These results are similar with the bilayer structure of FeGa/FeNi in another study [11]. Meanwhile, the spectra of FMR are almost symmetrical and the maximum peak strength indicates that the samples have better soft magnetic property [23,24].…”

“…We speculate this is because our sample shows isotropic magnetism. For FeGa/NiFe heterostructures deposited by sputtering, the resonance peak of µ and µ" is at about 1 GHz, which is a little higher than ours [11]. Compared with sputtering, the electrodeposition method can cause more defects and high roughness in films, which could induce different magnetic properties [26].…”

“…The coupling between the hard and soft ferromagnetic layers can effectively reduce the energy required to flip the moment of the film [20,21]. Some excellent works have involved the magnetoelastic and high-frequency properties of FeGa/magnetic heterostructures or multilayers, such as FeGa/FeNi and FeGa/Mn heterostructures [11,22]. The results show low coercivity, high permeability, and high strain sensitivity properties which make them extremely promising applications in high-frequency, strain coupled multiferroic systems.…”

“…Otherwise, FeGa materials can be used to optimize the static and dynamic magnetic properties of the sample. In particular, the soft magnetic properties of FeGaNi film and FeGa/FeNi multilayer films improve due to the introduced FeGa species [11,12]. Giant magnetoimpedance effect of Fe 75.5 Cu 1 Nb 3 Si 13.5 B 7 amorphous ribbon can be obviously enhanced by covering FeGa film on the surface of the sample [13].…”

Structural, magnetostatic, and magnetodynamic studies of Co/Mo-based uncompensated synthetic antiferromagnets

“…The investigated epitaxial Co/M o superlattices were deposited in a MBE system (Prevac) onto sapphire wafer substrates (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) oriented. All samples contained 5 Co/M o bilayers within the following structures:…”