Magnetic Field Sensor Based on Varistor Response

We present, in this paper, a non-conservative approach for building reliable magnetic field sensors based on the resistive and magnetoresistive responses of a varistor diode. These sensors can be built on a ceramic platform of a material which is a solid solution of the ilmenite–hematite consisting of 55 moles% ilmenite, FeTiO 3 , and 45 mole% of hematite, Fe 2 O 3 . This material is abbreviated as IHC 45. These sensors would be suitable for many applications in which a semiconductor Hall effect sensor is currently used. In addition, our ceramic sensors would be suitable for applications in high temperature, energy exploration and well logging, and radiation-dominant environments. The resistive mode sensor is expected to operate reliably and efficiently over the range of 0<H<4000 Oe and presumably beyond. In the magnetoresistive mode, it should operate satisfactorily for 500<H<4000 Oe range. Their sensitivity is highly current dependent. In its resistive mode, the sensor has the sensitivity of 107.4 $\text{m}\Omega $ /Oe at 0.5 mA which drops to a value of 24.2 $\text{m}\Omega $ /Oe at 2 mA. In the magnetoresistive mode, the sensor has the sensitivity of $142.6~\Omega $ /ln(Oe) and it is 15.6 $\text{m}\Omega $ /Oe at 2 mA. The magnetoresistive mode device also exhibits at room temperature a relatively large magnetoresistive ratio (MR%) of 57% at the modest field of just 4000 Oe making it potentially an attractive candidate for applications in spintronics and magneto-electronics.