Highlights (in construction)

 

2013 

Reversible control of magnetic interactions by electric field in a single-phase material

P. J. Ryan, J-W Kim, T. Birol, P. Thompson, J-H. Lee, X. Ke, P. S. Normile, E. Karapetrova, P. Schiffer, S. D. Brown, C. J. Fennie, & D. G. Schlom

Nature Communications 4, 1334  (2013) 

Intrinsic magnetoelectric coupling describes the interaction between magnetic and electric polarization through an inherent microscopic mechanism in a single-phase material. This phenomenon has the potential to control the magnetic state of a material with an electric field, an enticing prospect for device engineering. Here, we demonstrate ‘giant’ magnetoelectric cross-field control in a tetravalent titanate film. In bulk form, EuTiO3, is antiferromagnetic. However, both anti and ferromagnetic interactions coexist between different nearest europium neighbours. In thin epitaxial films, strain was used to alter the relative strength of the magnetic exchange constants. We not only show that moderate biaxial compression precipitates local magnetic competition, but also demonstrate that the application of an electric field at this strain condition switches the magnetic ground state. Using first-principles density functional theory, we resolve the underlying microscopic mechanism resulting in G-type magnetic order and illustrate how it is responsible for the ‘giant’ magnetoelectric effect.

 

2012

The magnetoelectric effect in transition metal oxides: Insights and the rational design of new materials from first principles

Turan Birol, Nicole A. Benedek, Hena Das, Aleksander L. Wysocki, Andrew T. Mulder, Brian M. Abbett, Eva H. Smith, Saurabh Ghosh, & Craig J. Fennie

Current Opinion in Solid State and Materials Science 16, Issue 5, October 2012, Pages 227-242

The search for materials displaying a large magnetoelectric effect has occupied researchers for many decades. The rewards could include not only advanced electronics technologies, but also fundamental insights concerning the dielectric and magnetic properties of condensed matter. In this article, we focus on the magnetoelectric effect in transition metal oxides and review the manner in which first-principles calculations have helped guide the search for (and increasingly, predicted) new materials and shed light on the microscopic mechanisms responsible for magnetoelectric phenomena.