High frequency characteristics of FeCoN thin films fabricated by sputtering at various (Ar+N2) gas flow rates

Abstract

FeCoN soft magnetic thin films with various nitrogen contents were fabricated by varying the gas flow rates of the argon and nitrogen gas mixture used during reactive rf magnetron sputtering. It was found that the resistivity of FeCoN film increased up to 211 μΩ cm with increasing nitrogen content. The film produced at the gas flow rate of 7 sccm exhibited the best soft magnetic properties with small coercivity and relatively large saturation magnetization. The microstructure of the films was examined by high-resolution transmission electron microscopy and α″-FeCo phase with very high saturation magnetization was observed in the films. The high-frequency properties of the FeCoN thin films were experimentally characterized and theoretically examined. The Hoffmann’s ripple theory was used to explain the permeability spectra for the films with strong magnetization dispersion. We found that the ripple effect is responsible for the large damping in the films, and those films with larger coercivities have stronger magnetization dispersion. With the gas flow rate of the argon and nitrogen gas mixture increasing from 0 to 15 sccm, the low-frequency permeability decreased from 680 to 245 and the ferromagnetic resonance frequency increased from 2.09 to 2.99 GHz.

Soft magnetic properties, high frequency characteristics, and thermal stability of co-sputtered FeCoTiN films

“…temperature above 150 • C [12,13]. The recently developed FeCoN films have an in-plane uniaxial anisotropy field usually exceeding 30 Oe, good magnetic softness, and high 0 M s above 2 T in the asdeposited states [14][15][16]. However, the magnetic thermal stability of the FeCoN films, especially in high frequency, has not been studied systematically so far.…”

High-frequency magnetic characteristics of Fe-Co-based nanocrystalline alloy films

“…Therefore, to explore specific soft magnetic films with excellent high-frequency characteristics, a number of approaches on Fe-Co-based nanocrystalline alloy films and multilayer films have been developed. For example, soft magnetic Fe-Co-N, Fe-Co-Ta-N and Fe-Co-Al-N thin films [16,17], and Ni 0.81 Fe 0.19 /(Fe 0.7 Co 0.3 ) 0.95 N 0.05 / Ni 0.81 Fe 0.19 thin films [18] with a sandwich structure have been studied. Multilayer consisting of discontinuous metal layers with native oxide surfaces has been fabricated using Co x Fe 100-x alloys [19].…”

Magnetic Properties, Microwave Characteristics, and Thermal Stability of the FeCoAlN Films

“…However, the uniaxial anisotropy fields of these films are typically below 20 Oe in the as-deposited states and can be reduced by annealing at temperatures above 150°C ( Ref 6,7). The recently developed FeCoN films have an in-plane uniaxial anisotropy field usually exceeding 30 Oe and good magnetic softness in as-deposited state (Ref [8][9][10]. However, the FeCoN films suffer from a low magnetic thermal stability ( Ref 11).…”