Since the work of Ørsted and Ampère in the 19th century, magnetism and magnetic fields have been intrinsically linked to electric currents. By contrast, the control of magnetism by electric fields is a topic that has elicited interest in scientific and engineering communities much more recently as the first experimental demonstration of a magnetoelectric effect occurred only in 1960. In the last 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. As an example, the energy needed to switch a nanomagnet by spin-transfer torque (~10 fJ) is several orders of magnitude larger than the energy needed to charge a magnetoelectric capacitor (~10 aJ). Thus, electric-field control is an enabling solution for many emerging applications of magnetism, which have been so far rendered uncompetitive due to large power dissipation.
The most efficient magnetoelectric systems are layered compounds consisting of piezoelectric and magnetostrictive materials. So far, studies of such magnetoelectric compounds have focused on large scale systems (mm to cm size) with very few reports on micrometer size devices. Moreover, mostly only the low frequency behavior of magnetoelectrics has been assessed. Microelectronic applications of magntoelectricity will however require devices with dimensions in the nanometer range and operate at GHz frequencies, i.e. at (sub-)nanosecond timescales. The main goal of the thesis will thus be the study of sub-micron devices including magnetoelectric compounds and their behavior at GHz frequencies, especially the magnetoelectric excitation of ferromagnetic resonance or spin waves (magnons). The thesis will range from materials oriented activities, such as the deposition and characterization of magnetoelectric compounds, device processing at imec’s nanofabrication facilities, as well as advanced electrical and optical characterization of such devices to assess their performance. This will allow to assess the potential of magnetoelectric devices for advanced spintronic applications, such as spin wave logic or magnetoelectric memories.
The thesis will combine the nanofabrication of devices and test structures with electrical (microwave) device characterization. A background in physics, applied physics, electrical engineering, or nanotechnology, together with interest in advanced spintronic applications and current topics in magnetism as well as enthusiasm for device nanofabrication are ideal.
Required background: (applied) physics, nanotechnology, electrical engineering
Type of work: 70% experimental, 20% modeling, 10% literature study
Supervisor: Joris Van de Vondel
Daily advisors: Christoph Adelmann, Florin Ciubotaru
The reference code for this PhD position is STS1712-03. Mention this reference code on your application form.