Defence in the field of engineering physics, Diego López González, M.Sc.

2017-09-29 12:00:00 2017-09-29 23:59:11 Europe/Helsinki Defence in the field of engineering physics, Diego López González, M.Sc. The title of the dissertation is: Control of magnetism in strain-coupled multiferroic heterostructures with in-plane and perpendicular magnetization http://physics.aalto.fi/en/midcom-permalink-1e78c79547ea4d08c7911e7acf2a70e99268e2f8e2f Otakaari 1, 02150, Espoo

The title of the dissertation is: Control of magnetism in strain-coupled multiferroic heterostructures with in-plane and perpendicular magnetization

29.09.2017 / 12:00
Lecture hall U1 (U154), Otakaari 1, 02150, Espoo, FI

Diego López González, M.Sc., will defend the dissertation "Control of magnetism in strain-coupled multiferroic heterostructures with in-plane and perpendicular magnetization" on 29 September 2017 at 12 noon in Aalto University School of Science, lecture hall U1 (U154), Otakaari 1, Espoo. Modern data storage devices use the magnetization of a material to store information. Improvement of these storage devices is facing difficulties due to material limitations and current-induced heating. This thesis explores coupling mechanisms that could reduce the energy consumption for future magnetic data storage and logic devices.

Modern data storage devices use the magnetization of a material to store information. Improvement of these storage devices is facing difficulties due to material limitations and current-induced heating. This thesis explores coupling mechanisms that could reduce the energy consumption for future magnetic data storage and logic devices. Specifically, I consider the coupling between a ferroelectric material and a ferromagnetic film. The application of a voltage across the ferroelectric layer changes its properties and, via strain transfer at the interface, it affects the magnetization of the neighboring ferromagnet. This magnetoelectric coupling mechanism results in strong coupling between ferroelectric and ferromagnetic domains, enabling control of magnetism by voltages rather than currents. Two main effects are reported. In systems where the magnetization and ferroelectric polarization are oriented parallel to the interface, the magnetic structure and energy of the walls that separate the magnetic domains are actively tunable. I demonstrate that this effect can be exploited to realize magnetic logic operations. For systems with alternating in-plane and out-of-plane domains, on the other hand, I show that electric fields can be used to drive magnetic domain walls reversibly without any assistance of a magnetic field or electric current.

Dissertation release (pdf)

Opponent: Dr. Carlos António Fernandes Vaz, Paul Scherrer Institut, Switzerland

Custos: Professor Sebastiaan van Dijken, Aalto University School of Science, Department of Applied Physics

Electronic dissertation: http://urn.fi/URN:ISBN:978-952-60-7572-3