Dynamic calculation of the responsivity of monodomain fluxgate magnetometers

Abstract

A model describing the dynamic response of a single-domain fluxgate magnetometer over a wide range of operating conditions in terms of a single measurement of a hysteresis loop or the permeability of the fluxgate's ferromagnetic core is presented. The model is based on the Landau-Lifshitz-Gilbert equation, which describes the dynamics of a coherently rotating ferromagnet. Measurements of the response of a permalloy thin-film fluxgate and a molybdenum-permalloy tube fluxgate demonstrate the accuracy and limitations of the model.

Energetics of magnetic ring and disk elements: Uniform versus vortex state

“…27,[44][45][46] However, it is usually the case that irregularities are inevitably present in small structures, 28,47-51 either as a consequence of the spatial resolution of the pattern writing or due to the different steps involved during the lithography process or, in the case of structures fabricated by deposition using a pre- defined mask, by mask irregularities or even due to the size of the crystallites in the case of polycrystalline elements 52 ͑which are of the order of 5 -20 nm, depending on film thickness, 53-56 substrate, 56,57 growth conditions, 58 growth rate, 59,60 deposition technique and thermal treatments 61 ͒. In addition, it is widely acknowledged that the edge roughness has an important role in the magnetic behavior of small elements, in particular in determining the nucleation field for magnetization reversal, 28,52,62-68 the dynamics of the magnetic reversal, 69 the effective magnetic energy of small elements 70 and in the stabilization of metastable equilibrium states.…”

Edge saturation fields and dynamic edge modes in ideal and nonideal magnetic film edges

“…Similarly, the edges of patterned magnetic thin films are expected to play an important role in the magnetic behavior of patterned elements. [1][2][3][4][5][6][7][8][9] The overall properties of a thin film device may depend on the edge properties through several mechanisms. For small structures, the device behavior may depend strongly on the edge properties simply because all locations in the structure are close enough to an edge to couple to the edge magnetization via exchange and dipole-dipole interactions.…”

Micromagnetic model of magnetization reversal of magnetically hard ultrathin dots and stripes

“…(6)]. The second one, * h; is more convenient for discussing magnetization reversal because * h ¼ À1 is the value for the Stoner-Wohlfarth model.…”

“…These studies are motivated by the development of devices requiring the use of such dots, like magnetic field sensors and magnetic random access memories (MRAMs) [2]. This has led to the outlining of the influence of parameters such as dot shape and size [3,4], edge roughness [5,6], magneto-crystalline anisotropy [7,8], and dot thickness [3,9]. Although numerical calculations can nowadays be performed with desktop computers, analytical modelling is still desirable for its capacity to predict rapidly general trends, in the form of power laws for example.…”