Self-Biased Bidomain LiNbO3/Ni/Metglas Magnetoelectric Current Sensor

Abstract

The article is devoted to the theoretical and experimental study of a magnetoelectric (ME) current sensor based on a gradient structure. It is known that the use of gradient structures in magnetostrictive-piezoelectric composites makes it possible to create a self-biased structure by replacing an external magnetic field with an internal one, which significantly reduces the weight, power consumption and dimensions of the device. Current sensors based on a gradient bidomain structure LiNbO₃ (LN)/Ni/Metglas with the following layer thicknesses: lithium niobate-500 μm, nickel-10 μm, Metglas-29 μm, operate on a linear section of the working characteristic and do not require the bias magnetic field. The main characteristics of a contactless ME current sensor: its current range measures up to 10 A, it has a sensitivity of 0.9 V/A, its current consumption is not more than 2.5 mA, and its linearity is maintained to an accuracy of 99.8%. Some additional advantages of a bidomain lithium niobate-based current sensor are the increased sensitivity of the device due to the use of the bending mode in the electromechanical resonance region and the absence of a lead component in the device.

Keywords: bidomain lithium niobate; current sensor; magnetoelectric effect; magnetoelectric gradient structure; magnetoelectric sensor.

Figure A1

Intrinsic magnetic fields in the bilayer magnetostrictive structure Ni/Metglas.

Figure 1

Schematic view of the magnetoelectric (ME) gradient structure.

Figure 2

Schematic representation of the setup for annealing samples of bidomain LN y + 128°-cut/Ni in the magnetic field.

Figure 3

Photo of one of the investigated structures based on bidomain LN/Ni/Metglas.

Figure 4

Dependence of the magnitude of the external magnetic field with error bars, at which point the linear section begins, on the nickel thickness.

Figure 5

Dependence of the ME voltage coefficient on the frequency of an alternating magnetic field for samples with different nickel layer thicknesses at zero bias field. Points are experimental data, solid lines are theoretical dependencies. When the experimental dependencies were taken, the amplitude of the alternating magnetic field was 1 Oe.

Figure 6

(a) Dependence of the resonance maximum of the ME voltage coefficient on the magnitude of the biased field for samples with different thicknesses of nickel. Individual points are experimental data, solid lines are theoretical dependencies. (b) Dependence of the resonance maximum of the ME voltage coefficient on the magnitude of the biased field for samples with thicknesses of nickel of 10 μm. Asterisks are experimental points and solid lines show the theoretical dependence. The dashed blue line is drawn through the first 4 experimental points using the least squares method.

Figure 7

The operating principle of the ME current sensor.

Figure 8

The block scheme of the ME current sensor.

Figure 9

(a) Designed body for the ME current sensor and (b) schematic description of the ME current sensor.

Figure 10

Output voltage versus measured current plot.