The field of is currently intensely researched for future ultralow power electronic applications. Such applications may be based on a as the logic element. While logic is currently transitioning from basic science to applied device research, many open issues remain to be demonstrated. A major roadblock is currently the energy that is needed to control the with electric signals. As a result, much work currently focuses on scalable and efficient transducers between electric and magnetic domains.
Many device concepts are typically based on the control of magnets by currents, for example via generated magnetic fields or more recently by spin-transfer or spin-orbit torques. However, such techniques are so far not sufficiently energy efficient. By contrast, the control the magnetization by electric fields instead of currents promises much lower power but many questions still remain. In recent years, magnetoelectricity has seen a renaissance due to technological and theoretical progress. The promise of magnetoelectricity is a large improvement in energy efficiency over current-based approaches. As an example, the energy needed to switch a by spin-transfer torque (~10 ) is several orders of magnitude larger than the energy needed to charge a capacitor (< 1 ). Thus, electric-field control is an enabling solution for many emerging applications, which have been so far rendered uncompetitive due to large power dissipation.
The most efficient systems are layered compounds consisting of piezoelectric and materials. So far, studies of such compounds have focused on large scale systems (mm to cm size) with very few reports on micrometer size devices. Improvements of the coupling are mainly expected from the optimization of the compound materials. Thinner piezoelectric layers lead to larger voltage responses of compounds, but the thickness scaling is highly challenging, e.g. due to dead layer effects. The usage of high materials, such as - or Tb-based materials also promises improved properties. This thesis will focus on the materials science and basic physics of such compounds. The thesis will start with the deposition of relevant thin films by pulsed laser deposition or sputtering and their characterization. To understand materials at the , characterization techniques for piezoelectric and responses at the will have to be designed using mechanical and micromagnetic modeling. Finally, the behavior of layered compounds will be studied at the . The work will be done in close collaboration with device engineers in the group working on devices.
A background in materials science, (applied) physics, or nanotechnology is ideal, together with interest in advanced applications and current topics in magnetism as well as enthusiasm for leading edge materials.
Required background: Materials Science/Engineering, Nanotechnology, Applied Physics, Physics
Type of work: 70% experimental, 20% modeling, 10% literature study
Supervisor: Marc Heyns
Daily advisor: Christoph Adelmann, Sean McMitchell, Florin Ciubotaru
The reference code for this position is 2020-009. Mention this reference code on your application form.
Chinese nationals who wish to apply for the CSC scholarship, should use the following code when applying for this topic: CSC2020-06.