Model for coil-less fluxgate

Abstract

Coil-less fluxgate is based on helical anisotropy in the ferromagnetic fluxgate core. We present and experimentally verify a simple model describing basic operation of this device. This model is an extension of previously presented two-domain model for classical orthogonal fluxgate, where the roles of longitudinal field is explained to be the domain wall movement between the two domains, whereas the circumferential field rotates the domains in opposite direction according to the direction of their magnetization. In this paper we extend this model to the case of helical anisotropy: we show how the decomposition of longitudinal and circumferential field along the anisotropy axes give rise to the typical gating curve of the coil-less fluxgate, and we explain the mechanism which gives its shifting under the effect of external field. Finally we experimentally validate the model by measuring the gating curve in case of helical anisotropy, and injecting DC current: as expected by the proposed model the gating curve looks like the case without helical anisotropy.