Tailoring Diverse Microwave Properties of High Magnetic Moment FeCo Nanofilms through Different Atom Arrangements

Abstract

The application of a pure FeCo film directly to devices is limited by the intrinsic properties of a homogeneous monolayer of the alloy, despite it having the highest saturation magnetization. A feasible methodology based on alternating current‐density electrodeposition to tune the microwave properties of FeCo films through diverse atom‐stacking arrangements is reported. The properties range from a large relative resonance permeability (up to 728 in the real part) to ultrahigh resonant frequency (up to 5.2 GHz), and extremely wide frequency dispersion (1.5–6.0 GHz); these are not observed in other materials or as a result of conventional doping methods. They are attained using different single‐layer, semi‐multilayer, and multilayer FeCo nanofilms, fabricated by diverse stacking arrangements of Fe and Co atoms during deposition in a single bath. This technique firstly exemplifies the significant effect of atom arrangement on magnetic inhomogeneity, nanoscale morphology, composition, crystal texture, stress, and damping, which in turn largely alters both the static and dynamic magnetic properties of the ferromagnetic film. These thin FeCo films might be used directly in various devices operating in the gigahertz frequency range.

The influence of structure and local structural defects on the magnetic properties of cobalt nanofilms

“…The extensive influence of phase transitions and critical phenomena on the working properties of the samples testifies the importance of a detailed study of structural transformations and possible stable states. Morphological analysis enables the identification of local defects in the crystal structure, which form different scale aggregates that can further serve as causes of deterioration of the target material functional characteristics [ 30 – 31 ]. Comprehensive studies in this area not only allow to establish the presence of structural heterogeneities and features, but also to formulate the main laws of their origin and development.…”

Structure and local structural defects influence on the magnetic properties of cobalt nanofilms

“…The extensive influence of phase transitions and critical phenomena on the working properties of the samples testifies to the importance of a detailed study of structural transformations and possible stable states. Morphological analysis makes it possible to identify local defects in the crystal structure, facts of forming different-scale aggregates, which can further serve as causes of deterioration of the target material functional characteristics [30,31]. Comprehensive studies in this area not only allow to establish the presence of heterogeneities and features of structure, but also to formulate the main laws of their origin and development.…”

Высокочастотная магнитная проницаемость однослойных и многослойных нанокомпозитов (Co-=SUB=-41-=/SUB=-Fe-=SUB=-39-=/SUB=-B-=SUB=-20-=/SUB=-)-=SUB=-x-=/SUB=-(SiO-=SUB=-2-=/SUB=-)-=SUB=-100-x-=/SUB=-

“…В работе рассмотрена высокочастотная магнитная проницаемость однослойных и многослойных нанокомпозитов аморфный ферромагнитный металл−диэлектрик, в которых в качестве ферромагнетика используется аморфный металл Co 41 Fe 39 B 20 . Хорошо известно, что сплав Сo 35 Fe 65 обладает наивысшей намагниченностью насыщения [4], а при добавлении бора в качестве аморфизатора сплав становится аморфным, при этом его удельное электрическое сопротивление значительно возрастает. Таким образом, использование состава Co 41 Fe 39 B 20 в композите позволяет в принципе получить материалы с рекордными высокочастотными парамет-рами.…”