We present a magneto-optical study of the three-dimensional topological insulator, strained HgTe, using a technique which capitalizes on advantages of time-domain spectroscopy to amplify the signal from the surface states. This measurement delivers valuable and precise information regarding the surface-state dispersion within <1 meV of the Fermi level. The technique is highly suitable for the p...

A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated...

Adviser: Shireen Adenwalla The interaction between ferromagnetic and ferroelectric films, the magnetoelectric effect, is a fascinating fundamental research area as well as having potential applications in magnetic data storage devices. We have investigated magnetoelectric coupling effects in thin film heterostructures, consists of metallic ferromagnet, cobalt, and the polymer ferroelectric [P(V...

We have investigated the magnetoelectric and magnetodielectric response in FeVO4, which exhibits a change in magnetic structure coincident with ferroelectric ordering at TN2≈15 K. Using symmetry considerations, we construct a model for the possible magnetoelectric coupling in this system and present a discussion of the allowed spin structures in FeVO4. Based on this model, in which the spontane...

Optical waveguide theory is essential to the development of various optical devices. Although there are reports on waveguides with magneto-optical (MO) and magnetoelectric (ME) effects, a comprehensive theoretical analysis considering these two effects has not yet been published. In this study, conventional extended by constitutive relations that account for both MO ME effects. Using theory, pr...

Title of Document: BOTTOM-UP MULTIFERROIC NANOSTRUCTURES. Shenqiang Ren, Doctor of Philosophy, 2009 Directed By: Professor Manfred Wuttig Department of Materials Science and Engineering Multiferroic and especially magnetoelectric (ME) nanocomposites have received extensive attention due to their potential applications in spintronics, information storage and logic devices. The extrinsic ME coupl...

Magnetoelectric responses are a fundamental characteristic of materials that break time-reversal and inversion symmetries notably multiferroics and, remarkably, of “topological insulators” in which those symmetries are unbroken. Previous work has shown how to compute spin and lattice contributions to the magnetoelectric tensor. Here we solve the problem of orbital contributions by computing the...

For rhombohedral multiferroelectrics, non-180° ferroelectric domain switching may induce ferroelastic and/or (anti-)ferromagnetic effect. So the determination and control of ferroelectric domain switching angles is crucial for nonvolatile information storage and exchange-coupled magnetoelectric devices. We try to study the intrinsic characters of polarization switching in BiFeO3 by introducing ...