Eliminating the Temperature Dependence of the Response of Magnetoelectric Magnetic-Field Sensors

Magnetic fields may be electrically detected by exploiting strain-mediated magnetoelectric coupling between a ferromagnet showing magnetostriction and a ferroelectric showing piezoelectricity. We argue that by electrically and thermally connecting two appropriately oriented anisotropic magnetoelectric elements that are identical, it is possible to cancel the strong unwanted pyroelectric response of the ferroelectric without cancelling the magnetoelectric response of interest. This result may be achieved using magnetoelectric elements that are merely similar, by measuring sensor voltage using an instrument with sufficiently low internal resistance. Using this strategy, we eliminate the influence of slow thermal fluctuations on the output of a sensor comprising two cheap magnetoelectric multilayer capacitors. This sensor can easily detect ~200 mT, suggesting the possibility of low-tech applications, e.g., detecting fields from cheap permanent magnets.