Magnetic sensors based on the planar Hall effect (PHE) sensors are attractive for applications where sub nano-Tesla field resolution is required. Previously, we have demonstrated that elliptical PHE sensors made of Permalloy exhibit field resolution of less than 200 pT/√Hz at 1 Hz for fields applied  perpendicular to the long axis of the magnetic ellipse [1,2] . Here we present PHE sensors made of two or three crossing ellipses and show that these sensors can be used to measure two axes of the magnetic field in the sensor plane while keeping similar size and noise level of a single axis sensor. Moreover, the two field components are measured with field a resolution of less than 200 pT/√Hz at 1 Hz in exactly the same region. The novel sensors can measure two axes of the magnetic field since in the overlap area of the ellipses there are effectively two perpendicular easy axes in the case of two crossing ellipses, and three easy axes 60 degrees apart from each other in the case of three crossing ellipses. Thus, for each remanent magnetic state in the overlap area, the sensor can measure the component of the magnetic field perpendicular to the direction of the remanent magnetization (see Figure). The simple design, low fabrication and integration cost, high performance and the smaller size make these novel PHE sensor useful for future device applications.

References

[1]. V. Mor, M. Schultz¹, O. Sinwani, A. Grosz, E. Paperno, and L. Klein, J. Appl. Phy., 111, 07E519 (2012).
[2]. A. Grosz, V. Mor, S. Amrusi, I. Faivinov, E. Paperno, and L. Klein, IEEE Sens. J., 16, 9 (2016).