Ultrahigh frequency magnetic susceptibility of Co and Fe cylindrical films deposited by pulsed laser ablation

Abstract

Soft magnetic Co and Fe films were deposited by pulsed laser ablation on Cu wires. The circular magnetic susceptibility of the cylindrical films was measured by applying an ac circular magnetic field at frequencies up to 6GHz. The measured ferromagnetic resonance frequency of the Co films was 2.5GHz, and the real part of the magnetic susceptibility at the lowest frequency of our measurements was 150. These results were explained as solutions of the Landau-Lifshitz-Gilbert equation, taking into account that the easy magnetization direction of the Co films was along the wire axis. Further measurements with an axial external magnetic field were consistent with this view. In contrast, for the Fe films, significant values of the circular magnetic susceptibility were measured only in the presence of external magnetic fields applied along the wire axis. This result indicated that the easy magnetization direction of the Fe films was not along the Cu wire axis. The magnetic anisotropy of both Co and Fe cylindrical films might originate from magnetoelastic effects, resulted from built-in stress. The different behaviors of the Co and Fe cylindrical films would then be attributable to the different signs of their magnetostriction constants λs.

Soft magnetic nano-strings simultaneously grown and sculpted on Si micro-cantilevers

“…Structural and magnetic studies of our Co PLD films revealed that they were formed by nanograins with an average grain size of E 1-2 nm [5] and they behaved as magnetically soft [2,[5][6][7].…”

“…[4]. In particular, we have shown that Co nanostructured films obtained by pulsed laser deposited, PLD, with m o M s E1.4 T, exhibited these soft magnetic [2], magnetoelastic [5,6] and ultra high frequency properties [7].…”

Broad UHF ferromagnetic resonance of iron rich-aluminum pulsed laser deposited thin films

“…In this way, materials with relatively high resistance have been used to suppress noise in high frequency magnetic devices [5]. Good candidates are the FeCo-based films [6,7]. The improvement of the soft magnetic properties of these films can be achieved by adding other elements [8], by using an underlayer [9], by using CoFe-based oxides or nitrides, etc.…”

The structure and microwave permeability of thin cobalt films

“…Thin Co films have been actively studied in con nection with designing devices for high density infor mation storage [1], magnetic field sensors [2], and applications for the UHF range [3][4][5]. The processes of magnetic film growth are sensitive to small changes in the deposition parameters, which makes it possible to control the magnetic properties in a wide range [6].…”

“…It is known from various sources that Co films possess the ferromagnetic resonance under the frequency f res = 2.5 [4] or 10 [3,13,14] GHz. An increase in the Co film thickness results in a broad ening of the FMR line [13,15].…”