Materials Science and Engineering Seminar Series: Eckhard Quandt
Giant magnetoelectric coefficients in (Fe90Co10)78Si12B10-AlN thin film composites
Professor and Chair
Inorganic Functional Materials
Institute for Materials Science
Christian-Albrechts-Universität zu Kiel, Germany
Magnetoelectric (ME) composite materials show ME coefficients that are larger than that of natural multiferroics by up to several orders of magnitude. These composites have high potential as very sensitive ac magnetic field sensors. Special features are their passive nature, their capability to detect magnetic fields at very low frequencies, their large dynamic range with linear response and their enhancement at certain frequencies by mechanical resonances. By a suitable combination of magnetic shape anisotropy and field annealing it is possible to obtain a sensor element that has a pronounced sensitivity in only one dimension being a component of a 3-dimensional vector field sensor, which is highly desirable for applications like magnetoencephalography or cardiography as a replacement for todays sensors based on bulky and expensive SQUIDs.
In this work the fabrication and unique properties of such a thin film ME 2-2 composites are demonstrated. It consists of AlN and amorphous (Fe90Co10)78Si12B10 (Metglas) layers, that were deposited by magnetron sputtering on Si (100) substrates (1). Upon magnetic field annealing these ME composites show an uniaxial magnetic anisotropy and an extremely high ME coefficient of up to 1800 V/cmOe at mechanical resonance (2) and about 3 V/cmOe out of resonance.
(1) H. Greve, E. Woltermann, H.-J. Quenzer, B. Wagner, E. Quandt, Appl. Phys. Lett. 96, 182501 (2010).
(2) H. Greve, E. Woltermann, R. Jahns, S. Marauska, B. Wagner, R. Knöchel, M. Wuttig, E. Quandt, Appl. Phys. Lett. 97, 152503 (2010).
Funding via the DFG Collaborative Research Center SFB 855 "Magnetoelectric Composites Future Biomagnetic Interfaces" is gratefully acknowledged.