Abstract
A phase-sensitive dc magnetometer is developed by combining a pair of permanent magnets, an electromagnetic coil, and a magnetostrictive–piezoelectric laminate in one direction to form a four-phase magnetic–electromagnetic–magnetostrictive–piezoelectric heterostructure. The dc magnetic field sensing in the magnetometer is based on the detection of the phase difference between the off-resonance magnetoelectric voltage manipulated by the dc magnetic field to be measured and the resonance electric current referenced at zero dc magnetic field, both under a preset bias magnetic field. The theoretical and experimental results confirm a high and linear dc magnetic field sensitivity of –0.21 °/Oe over a positive and negative dc magnetic field range of ±150 Oe with a small nonlinearity of 1.7%. The magnetometer has the ability to determine dc magnetic field direction and its sensitivity is independent of zero-field resonance electric current amplitude.
Highlights
We report theoretically and experimentally a phase-sensitive dc ME magnetometer having a magnetostrictive– piezoelectric (MS–PE) laminate wound with an electromagnetic (EM) coil and sandwiched between a pair of permanent magnets in one direction to give a four-phase magnetic–EM–MS–PE heterostructure
The θVME − θI spectra essentially follow the arctan trends for all Hdc in that their slopes give an approximately linear response of θ with respect to Hdc when fr0/fr is close to unity
If I is kept as Ir0 with fr0 = 115.8 kHz, an increase/a decrease in Hdc from 0 Oe will decrease/increase the value of θ0 = θVMEr0 − θIr0 = 90◦ to become θ = θVME − θIr0
Summary
Magnetometers based on an extrinsic magnetoelectric (ME) effect in magnetostrictive– piezoelectric (MS–PE) laminates have stimulated considerable scientific research interest and technological development opportunity in the past decade owing to their promising features of passive sensing, high sensitivity, low noise, and wide bandwidth in comparison with conventional Hall-effect and magnetoresistance magnetometers.[1,2] the magnetic field sensing in most ME magnetometers is built on an extrinsic ac ME effect in which the magneto-mechano-electric coupling between the constituent MS and PE phases of the laminates is achieved dynamically under an applied ac magnetic field,[3,4] and the resulting magnetometers are classified as ac ME magnetometers.[5,6,7,8] The principal limitation in these ac ME magnetometers is their inability to measure dc magnetic fields because the extrinsic ac ME effect as characterized by an ME voltage or charge response is generally weakened by the decay of PE charge with time in the PE phase below 100 Hz.[1,2,3]Recently, a current-mode dc ME magnetometer was proposed based on an ac electric currentcontrolled, dc magnetic field-induced Lorentz force effect in a conductive–PE heterostructure with or without dc magnetic biasing.[5,6] An ac electric current-controlled dc magnetic field sensitivity of 3–170 μV/Oe/A was obtained for dc magnetic fields up to 2 kOe under an ac control current of ≤300 mA at
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