Magneoelectric composites have potential for many exciting applications in sensing and energy transduction. Two-phase magneoelectric composite consist of piezoelectric and magnetostrictive phases. Magneoelectric composite devices convert magnetic energy to electrical energy (and vice-versa) through a two-step process: magnetic energy is first converted to mechanical energy via linearized magnetostriction in the magnetic part of the magneoelectric composite, and then the mechanical energy is converted to electrical energy via the piezoelectric component through elastic coupling.
The performance of a magneoelectric device is determined by material properties, phase connectivity and interface quality. A common connectivity is the laminate structure, owing to ease of fabrication and simple operation. Different options are matrix embedded nanoparticles, which have a larger interface area, however are more complicated for fabrication. A lower interface quality can reduce the elastic coupling between the phases and the subsequent device performance.
In this study, we examined whether, and to what extent, a roughening of the interface contributes to increased coupling and improved performance. This is done through finite element simulation (COMSOL Multiphysics), with a given set of materials, while changing the interface geometry. The simulated structure consisted of a 2 layers laminate composite: AlN as a piezoelectric and Terfenol-D as the magnetostrictive, with dimensions in the mm range. The composite’s on- and off-resonance open circuit electrical output under DC and AC magnetic fields was studied as a function of the microscale features of the interface.
We found that the right degree of surface roughening results in up to 50-60% enhanced magnetoelectric coupling – while conserving the composite phases mass ratio. We will discuss the different factors contributing to such enhancement in terms of stress transfer and overall structure mechanical properties. This study opens up a route for more efficient magnetoelectric applications.

Here we present results obtained on epitaxial ferroelectric thin films with ABO3 structure. Epitaxial thin films offer advantages in terms of controlled growth and strain engineering, which increases their ability to be tailored for specific applications. Materials that are ferroelectric and have a perovskite structure and ABO3 show spontaneous polarization that can be induced by several factors, such as light, temperature, mechanical stress, and an electric field. These materials can play a significant role in various electronic and sensing applications or energy harvesting. Here, conductive oxides SrRuO3 (SRO) and LaSrMnO3 (LSMO) were used as bottom electrodes for all structures that were deposited on SrTiO3 (001) substrates. The electrical characterizations of the epitaxial layers with different thicknesses were performed on capacitor like geometry. For this, the top SRO/Au electrodes were deposited by PLD and magnetron sputtering using a shadow mask and defining
ferroelectric capacitors of 100 μm2 area. Our studies revealed that the utilization of pulsed laser beam deposition is suitable for obtaining ultrathin films with thicknesses measuring less than 5 nm. Which allowed us to evidence the impacts caused by the polarization orientation on the band structure or the presence of self-doping phenomena. We also found one way to tailor the PbZrTiO3 (PZT) properties through doping. The studies that we performed on doped PZT followed to examine the impact of 1% Fe and Nb doping on the electrical characteristics of epitaxial PZT films. In the same time we investigate whether changing from n-type (Nb) to p-type (Fe) doping may influence the polarization orientation in the as-grown layers.

Quantum materials gain an increasing interest in the field of electronics research. One exciting opportunity is heterostructures of magnetic oxides (MO) and topological insulators (TI) exhibiting unique combined properties and emergent interfacial properties. Recent studies on the topological insulating dichalcogenide systems, forming heterostructures with magnetic compounds reveal that such systems exhibit emergent interface ferromagnetism, quantum anomalous Hall effect, enhancement of magnetic order, and ordering temperatures and topological surface states extending into the magnetic material. For the materials possessing inherently different crystal structures, an important first step is to ensure high-quality interfaces and the proper connectivity. In this work, we focus on structural engineering of TI Bi2Te3 (BT) grown on (001) & (111) oriented magnetic perovskites. The aim of the research is to establish a precise BT growth control towards a thorough understanding of magnetic interactions at magnetic perovskite-2D topological insulator interfaces. BT thin films are deposited by pulsed laser deposition (PLD) directly onto (001) and (111)-oriented SrTiO3 (STO), La0.7Sr0.3MnO3 (LSMO) and LaFeO3 (LFO). In structural analysis with SEM, AFM and XRD, we show that high quality BT films can be grown by PLD on high lattice mismatch substrates. We employ Raman spectroscopy and vibrating sample magnetometry (VSM) to confirm the proper BT stoichiometry and investigate the effect on macroscopic magnetism of ferromagnetic LSMO, respectively. By utilizing different substrate orientations, as well as magnetic characteristics, heterostructure interactions can be tuned. This tunability can be used to further probe systematically how the oxide spin axis couples to the van der Waals material, and what is the effect on the topological insulator properties.