Nanoscale Science Department

Research efforts in the Department are centered on nanoscale science and technology with a focus on the bottom-up paradigm. The aim of the interdisciplinary research at the interface between physics, chemistry and biology is to gain control of materials at the atomic and molecular level, enabling the design of systems and devices with properties determined by quantum behavior on one hand and approaching functionalities of living matter on the other hand.



<p style="text-align: justify;">Carbohydrate Self-Assembly at Surfaces: <br />STM Imaging of Sucrose Conformation and Ordering on Cu(100)</p>

Saccharides, colloquially known as sugars, are ubiquitous biomolecules taking part in nearly every biochemical process. However, little is known about their interaction and assembly at surfaces. Exploiting electrospray ion-beam deposition we were able to explore the self-assembly of the disaccharide sucrose on a Cu(100) surface and to image the molecule with subunit resolution by scanning tunneling microscopy. Using a multistage modeling approach, we could rationalize the conformation on the surface as well as the interactions between the sucrose molecules. Our work lays the groundwork for understanding complex oligosaccharides and their structure-function relationship.

Photon Superbunching from a Generic Tunnel Junction
When a single electron is made to tunnel across a vacuum gap, it may occasionally produce not just one, but two photons at a time. When these very rare events are produced in excess, the result is a phenomenon known as photon superbunching. With this finding, we have expanded the range of fundamental processes that can be controlled in a tunnel junction environment.
<div style="text-align: justify;">Spin Hall Photoconductance in a 3D Topological Insulator</div>
The strong spin-orbit coupling in three-dimensional topological insulators imparts a transversal spin Hall effect supported by their bulk states. It is demonstrated that the resulting spin accumulation at the lateral edges of Bi2Te2Se nanoplatelets can be effectively read out at room temperature through the local detection of a helical, bias-dependent photoconductance. The spin accumulation is further supported by the observation of a finite bias-dependent Kerr angle at the nanoplatelet edges.


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