A method to measure the complex permeability of thin films at ultra-high frequencies

Korenivski, Vladislav; Dover, R. B. van; Mankiewich, P. M.; Zhi, Ma; Becker, A.; Polakos, P.; Fratello, V. J.

doi:10.1109/20.539283

Cited by 52 publications

(22 citation statements)

References 9 publications

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“…The permeability in this case is given by the ratio between the saturation magnetization (M S ) and the anisotropy field (H K ). This value can be maintained up to the ferromagnetic resonance (FMR) frequency [1] which is given by f r ¼ 2pg(4pM S H K ) 1/2 , were g is the gyromagnetic constant (2pg ¼ 2.8 MHz/Oe).…”

mentioning

confidence: 99%

Structure and Soft Magnetic Properties of Fe?Zr?N Films

Chezan

Craus

Чеченин

et al. 2002

phys. stat. sol. (a)

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Soft magnetic films with high saturation magnetization and controllable uniaxial anisotropy are required for future high frequency applications. However, the origin and magnitude of the induced magnetic anisotropy are still a contradictory issue. In this paper we show the influence of the structure and composition of sputtered Fe-Zr-N films upon the coercivity and the induced uniaxial magnetic anisotropy. We have found that the increase of the nitrogen content of the sputtered films leads to a reduction of the grain size and a strong increase of the uniaxial anisotropy. The value of 20 Oe for the anisotropy field combined with a saturation magnetization of 20 kG found in a film with average grain size as low as 10 nm gives a ferromagnetic resonance frequency of 1.8 GHz and a roll-off frequency of 1.2 GHz. Such a film is a promising candidate to be used as an ultra-high frequency inductor.Introduction Soft magnetic materials with high saturation magnetization and controllable uniaxial anisotropy are required for future high frequency inductors as well as for high-density recording heads. Such materials must have a well-controlled domain pattern with the magnetization, in the absence of an external magnetic field, oriented in most of the domains parallel to the direction of the anisotropy axis. The hysteresis loop will be a rectangle in the easy direction (domain wall movement) and a straight line in the hard direction (spin rotation). When an external ac field is applied perpendicular to the easy axis the magnetization oscillates with the field. The permeability in this case is given by the ratio between the saturation magnetization (M S ) and the anisotropy field (H K ). This value can be maintained up to the ferromagnetic resonance (FMR) frequency [1] which is given by f r ¼ 2pg(4pM S H K ) 1/2 , were g is the gyromagnetic constant (2pg ¼ 2.8 MHz/Oe).The magnetic domain pattern can be controlled by reduction of the grain size below the ferromagnetic exchange length (the contribution of the magnetocrystalline anisotropy is averaged out) and by introducing an uniaxial anisotropy. Promising materials for this purpose were found to be FeMN thin films, with the typical M being Ta [2], Cr [3], Zr [4], etc. In the past decade large efforts were spent in optimising the microstructure and composition of these materials in order to get optimal magnetic properties. However, the information about the origin and magnitude of induced uniaxial anisotropy is often contradictory. In this paper we show the influence of the nitrogen content on grain size, coercivity and induced anisotropy in Fe-Zr-N films.

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confidence: 99%

Structure and Soft Magnetic Properties of Fe?Zr?N Films

Chezan

Craus

Чеченин

et al. 2002

phys. stat. sol. (a)

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“…In that case, the effective permeability is m eff ¼ 1 due to the absence of the magnetic film. e empty eff ðf Þ could be easily obtained from the measured values of the reflection coefficient S empty 11 ðf Þ by using Expression (5) for an empty strip line and was calculated to the following equation …”

Section: Measurement Procedures and Data Processingmentioning

confidence: 99%

“…However, due to the relatively big size and complexity their sensitivity rapidly drops at GHz frequencies in consequence of dimensional resonance and conductivity effects E-mail address: klaus.seemann@imf.fzk.de (K. Seemann). [5]. For the GHz range the second group of measurement techniques is more suitable.…”

Section: Introductionmentioning

confidence: 98%

A new strip line broad-band measurement evaluation for determining the complex permeability of thin ferromagnetic films

Bekker¹,

Seemann²,

Leiste³

2004

Journal of Magnetism and Magnetic Materials

167

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“…An accurate and reliable result could be provided in the MHz frequency range in the coil technique. When the frequency reaches higher to the GHz range, however, the accuracy decreases due to the dimensional resonance and conductivity effects at high frequency [2]. The usual transmission line broadband measurement method can be divided into two types: the transmission and reflection method (two-port technique) and the reflection method (one-port technique).…”

Section: Introductionmentioning

confidence: 99%