We study interaction of light with various materials at the nanoscale via nanoantennas, and apply this knowledge in creating novel optical metamaterials and metadevices, light-operated information processing and storage, actively-controlled photochemistry and sustainable energy management.
Researchers at the Department of Physics have carried out projects to make magnetic storage operate with light, making it more energy efficient, smaller, and about 10 000 times faster than what is currently available.
“To achieve this, we take the primely efficient light concentrators, optical nanoantennas, and make them channel light to the nanoscale, where we put magnetic materials,” says Alexandre Dmitriev, professor at the Department of Physics.
We contribute to the Gothenburg Science Festival 2020 with the entry Nano-carpets of gold
"This is an electron microscope image of polymer micro-balls, packed on a surface, covered/wrapped by a thin (10 nanometers) carbon film with gold nano-dots / gold dust (100 nm size) on top. The carbon film itself is actually invisible in the picture. This nanofabrication method, allowing us to wrap and cover things at the nanoscale – just like in real macro-life – was developed by researchers at Chalmers and University of Gothenburg.
If we can wrap small things, we can protect or add extra functions to them. Wrapping live bacteria this way might help extract all kinds of information from their surface. This could for example be used for bacterial diagnostics – like putting thousands of little sensors on the ‘beast’.
Invisible carbon carpets might also work as membranes in catalysis, since they are very porous. Then the dots are the catalysts, designed to speed up selected chemical reactions when gas flows through them. Since we can stack hundreds of such membranes together, we can save lots of energy on producing various chemical compounds. It can potentially make the production of chemicals ‘greener’ by letting us use less environmentally harmful catalysts."
We finished coordinating our massive EU Horizon2020 FET-Open project FEMTOTERABYTE ‘Spinoptical nanoantenna-assisted magnetic storage at few nanometers on femtosecond timescale’, aiming at magnetic hard drives that are 100 times smaller and 10,000 times faster than the ones we use today.
Our spin-off project on solar nano-thermal windows taking part in VentureCup Sweden Start-Up 2020. We use nanoantennas on regular glass windows to make them warm-up using sunlight. The glass stays transparent and doesn’t change the color of the sunlight, it is color-neutral. Solariton was a Chalmers School of Entrepreneurship project in 2019-2020.
Future ultrafast and energy-efficient magnetic memory
With the exponential increase for the data cloud storage needs - we envision the magnetic storage of the future to ‘run on light’, i.e., read/write with light, be more energy-efficient, much smaller and about 10 000 times faster than what’s currently available. To achieve that, we concentrate the femtosecond pulses of light by optical nanoantennas combined with magnets.
We reveal magnetically tunable optical effect in a special kind of artificial materials, called hyperbolic metamaterials, displaying nontrivial optical properties, such as conductive behaviour along particular spatial directions and insulating behaviour along others. This is a possible step towards future magnetically-controlled optics.
For the first time, the studies of single-molecules magnets go out of the large synchrotron facilities, as the ultra-sensitive detection of the magnetic properties of just a few monolayers of the molecular magnets can now be studied with conventional optical magnetic circular dichroism, strongly enhanced by the nanoantennas. This opens the long-envisioned path towards using single-molecule magnets as the ultimate atom-sized memory units. Article in Materials Horizons
How to melt gold at room temperature at the atomic scale:
We devised optically chiral polarizing transparent surface that can be changed in real time by more than 100% with the externally applied low magnetic field. Future directions include the tunable lenses, on-chip beam-steering (for example, for FaceID light sources), dynamic holograms and other exciting optical functionalities.
In a large EU (FET-Open) project collaboration, we conceived an ultra-thin (effective thickness about 800 nanometers) single-crystalline silicon solar cell with the efficiency of 9.6%. For comparison – conventional crystalline Si solar cells measure 200 microns in thickness and have the efficiency of slightly above 20%. The prospects are open for the highly efficient and semi-transparent solar cells.
Building on the magnetoplasmonic sensing principles, established in our previous works, we pushed the limits of detection and the figure-of-merit of nanoplasmonic biological and chemical sensing several orders of magnitude. News feature at Phys.org