a1 Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen (GREYC), CNRS UMR 6072 – ENSICAEN and the University of Caen Basse Normandie, France 14050 Caen Cedex,
a2 Materials Science and Engineering, Virginia Tech, Virginia 24061, USA
a3 SAIC, McLean, Virginia, USA
With the development of applications involving high sensitivity ferromagnetic-ferroelectric laminates, a systematic analysis of the noise floor for magneto-electric (ME) laminated sensor has become crucial. We report and discuss the results of such an analysis on the noise floor of magnetostrictive-piezoelectric laminates in terms of the magnetic noise spectral density at room temperature. The noise floor of highly sensitive ME laminates with a JFET charge amplifier detection method has been studied. A good correlation was found between the theoretical and experimental noise curves within the measurement bandwidth. The dominating noise sources were found to include the dielectric loss noise, mechanical loss noise of the magneto-electric laminates and the noise sources of the charge amplifier. By using an appropriate low noise JFET charge amplifier, the noise contributions from the amplifier can be made negligible, enabling the measurement of the intrinsic noise of the ME laminates sensor. Thus, we have shown that at low frequencies, below the resonant frequency, the dielectric loss noise predominates with a one-per-root-frequency dependence whereas, around the resonance, the mechanical loss noise prevails over all other noise sources as expected from our theoretical analysis.