Lauren M. Garten - Determining the Impact of Strain on Magnetoelectric Coupling in Artificial Multiferroic Heterostructures
From Katie Gentilello
Magnetoelectricity presents a unique opportunity to control the magnetic response of a material with an applied electric field or vice versa. Unfortunately only a few materials exhibit controllable magnetoelectric coupling (ME) within a single phase, and even then, the response is typically small and below room temperature. One route to enhance ME coupling is to create a composite between a ferroelectric and ferromagnetic material. This type of ME coupling can be mediated in multiple ways, but the current most successful method is through strain transfer across an interface. These artificial multiferroic heterostructures can exhibit ME coupling up to six orders of magnitude larger than within a single material. Still further improvement must be made before ultra-low power memory, logic, magnetic sensors, and wide spectrum antennas can be realized. In this talk I will describe how ME coupling can be enhanced by simultaneously exploiting multiple strain engineering approaches. This work is conducted on heterostructures composed of Fe0.5Co0.5/Ag multilayers on (011) Pb(In1/2N1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 piezoelectric crystal substrates. When grown and measured under strain these heterostructures exhibit an effective converse magnetoelectric coefficient on order of 10-5 s/m: the highest directly measured, non-resonant value to-date. Additionally, this response occurred at room temperature and at low electric fields (< 2 kV/cm). This large effect is enabled by the magnetization reorientation caused by changing the magnetic anisotropy with strain and using multilayered magnetic materials to minimize the internal stress from deposition. This work highlights how multicomponent strain engineering enables enhanced magnetoelectric coupling in heterostructures and provides an approach to realize new energy efficient magnetoelectric applications.