Calculation of Shape Anisotropy for Micropatterned Thin Fe–Ni Films for On-Chip RF Applications

Abstract

Abstract-We present a self-consistent calculation of the effective anisotropy of patterned, integrated ferromagnetic films. For comparison, experimental data were obtained from electroplated thin (0.5 m) Ni-Fe films with different patterns. The effective anisotropy of patterned samples was increased by shape demagnetizing effects from just 10 Oe up to 100 Oe. The samples with suitable characteristics were subsequently used as cores for on-chip inductors and microstrips.

Integrated Tunable Magnetic RF Inductor

“…Furthermore, increased, achieving the highest value for this set of inductors, by bringing the aspect ratio (FMW/FML) to one [ Fig. 2(b)], in agreement with the expected behavior of the demagnetization field inside the magnetic core [7], [8]. The observed gradual drop in with increasing frequency [ Fig.…”

“…clearly distinguish three regions denoted by A, B, and C. In regions A and C, the permeability practically remains constant with increasing magnetic field, with a high permeability in A and a low permeability in C. In the intermediate region (B), the permeability decreases with increasing magnetic field. The strong dependence of the permeability on the external magnetic field in region B can be explained by taking into account the nonuniform distribution of magnetization inside the core [7]. Furthermore, the threshold field required for the onset of this behavior depends on the mutual balance of internal shape-induced demagnetizing fields in the easy and hard directions and for the set of rectangular FM samples of either the fixed width (FMW) or the fixed length (FML) is minimum for square samples (FML = FMW) [7], [8].…”

“…The strong dependence of the permeability on the external magnetic field in region B can be explained by taking into account the nonuniform distribution of magnetization inside the core [7]. Furthermore, the threshold field required for the onset of this behavior depends on the mutual balance of internal shape-induced demagnetizing fields in the easy and hard directions and for the set of rectangular FM samples of either the fixed width (FMW) or the fixed length (FML) is minimum for square samples (FML = FMW) [7], [8]. The strong dependence of the permeability on the external dc field in the intermediate region (B) lies at the basis of the tunable inductor.…”

Integrated RF inductors with micro-patterned NiFe core

“…The demagnetizing fieldH dem ðrÞ in the patterned magnetic film (i.e., single rectangular prism and prism array) is non-uniform, and can be obtained by selfconsistent numerical calculation of solving [22,23] H dem ðrÞ ¼ rwðrÞ ð 7Þ…”

“…The thickness of the SIO 2 core is 0.5 lm. tion of the magnetization in the samples was calculated in a self-consistent way [22]. The result for the sample #13-2 (aspect ratio 2:1) is plotted in Fig.…”