Engineering new limits to magnetostriction through metastability in iron-gallium alloys
Peter Meisenheimer, Rachel Steinhardt, Suk Hyun Sung, Logan Williams, Shihao Zhuang, Mark Nowakowski, Steve Novakov, Mustafa Mert Torunbalcı, Bhagwati Prasad, Christian J. Zollner, Zhen Wang, Natalie M. Dawley, J. Schubert, Allen H. Hunter, Sasikanth Manipatruni, Dmitri E. Nikonov, Ian A. Young, Long‐Qing Chen, Jeffrey Bokor, Sunil A. Bhave, R. Ramesh, Jia‐Mian Hu, Emmanouil Kioupakis, Robert Hovden, Darrell G. Schlom, John T. Heron
Abstract
Abstract Magnetostrictive materials transduce magnetic and mechanical energies and when combined with piezoelectric elements, evoke magnetoelectric transduction for high-sensitivity magnetic field sensors and energy-efficient beyond-CMOS technologies. The dearth of ductile, rare-earth-free materials with high magnetostrictive coefficients motivates the discovery of superior materials. Fe 1− x Ga x alloys are amongst the highest performing rare-earth-free magnetostrictive materials; however, magnetostriction becomes sharply suppressed beyond x = 19% due to the formation of a parasitic ordered intermetallic phase. Here, we harness epitaxy to extend the stability of the BCC Fe 1− x Ga x alloy to gallium compositions as high as x = 30% and in so doing dramatically boost the magnetostriction by as much as 10x relative to the bulk and 2x larger than canonical rare-earth based magnetostrictors. A Fe 1− x Ga x − [Pb(Mg 1/3 Nb 2/3 )O 3 ] 0.7 −[PbTiO 3 ] 0.3 (PMN-PT) composite magnetoelectric shows robust 90° electrical switching of magnetic anisotropy and a converse magnetoelectric coefficient of 2.0 × 10 −5 s m −1 . When optimally scaled, this high coefficient implies stable switching at ~80 aJ per bit.