Electronic & Magnetic Materials & Devices
Group Leader: Saw-Wai Hla
The objective of the Electronic and Magnetic Materials and Devices (EMMD) group at the CNM is to discover, understand, and utilize new electron and spin-based materials and phenomena in constrained geometries. Potential benefits include reduced power dissipation, new medical imaging methods and therapies, improved efficiency of data storage by spin current and electrical field-assisted writing, and enhanced energy conversion in photovoltaic devices.
- Understanding complex magnetic order and coupling phenomena: Magnetic nanostructures are prone to complex magnetic ordering phenomena that do not occur in the bulk and that will have strong impact on the further development of functional magnetic nanostructures. Basic science on the influence of demagnetizing effects, geometrical frustration, next-nearest neighbor exchange interactions, unusual anisotropy values, and the spin-orbit interaction at reduced dimensionality are performed with a special focus on temperature-dependent magnetic order-disorder transitions.
- Exploring energy, charge, and spin dynamics in optically active nanoscale systems: We are pursuing laser microscopy and spectroscopy to investigate electronic and magnetic behavior of single particles in the solid state, probing dynamics on ultrafast time scales and exploring the limits of quantum coherence. By combining these capabilities with local scanning probes in ultrahigh vacuum (UHV), we are developing a new experimental capability with several advantages: (a) direct correlation of optical properties with atomic-scale spatial information; (b) local measurement of photo-generated charge with a scanning probe microscope (SPM) tip; and (c) nanofabrication of novel atomic-scale optical systems with the scanning probe. Experimental studies aim to elucidate fundamental energy transfer processes in next-generation photovoltaic materials and develop a new platform for quantum state manipulation.
- Understanding charge and spin transport: The interaction between electrical currents and all kinds of matter is highly relevant for future technological developments of, for example, magnetic sensors and organic solar cells. We perform research on charge and spin transport on surfaces as well as through single atoms, molecules, supramolecules, nanoparticles, and nanocomposites.
- Controlling synthesis of materials with tailored electronic and magnetic properties: With recent advances in atomically controlled preparation techniques, the engineering of new materials with seemingly exclusive properties comes into reach. One example is the combined existence of ferroelectricity and ferromagnetism (multiferroics), and the development of magnetic materials in which the magnetization direction is switched by an external electrical field. We perform controlled synthesis of new nanoscale materials by the combination of theoretical methods with state-of-the-art molecular beam epitaxy and colloidal chemistry.
- Polymeric materials and templates: Self-assembly processes in homopolymer and diblock copolymer films offer an inexpensive route for new concepts in solar cell applications and as templates for nanopattern transfer. Fundamental properties of diblock copolymers are investigated, including their self-organization behavior, their utilization as etch masks or active materials in organic and hybrid nanocomposite structures for photovoltaics, and the charge transport in the resulting nanomaterials.
- Functionalization of colloidal nanoparticles: Composites made of noble metal and magnetic materials exhibit extraordinary properties. For example, surface plasmon excitation in noble metals may enhance local electric magnetic field dramatically, leading to nonlinearity and an enhanced magnetooptical response. Furthermore, noble metal shells can be functionalized with complex ligand molecules which specifically target certain receptor proteins. Using magnetic cores with surface binding ligands, we envision efficient targeting of cancer cells through external magnetic fields.