Modern nanotechnology instruments can routinely produce nanostructures with dimensions in the range of the key length scales, such as the electron wavelength. These nanostructures display a range of unique properties that are relevant to fundamental studies as well as potential applications.
Advanced nanomaterials: Casimir researchers use high-end thin film deposition technologies to create new quantum nanomaterials. The composition of each atomic layer of artificial crystalline structures can be designed and controlled with the aim of exploring the physics of unusual electron systems, such as complex metal oxides. These nanomaterials display an amazing variety of different electronic properties such as magnetism and superconductivity at much higher temperatures than any other material. In other groups the focus is on producing single-spin qubits in semiconductor quantum dots and on electronic transport in mesoscopic graphene devices. The interest is in the basic properties of these systems as well as in possible applications in quantum information processing. In a third group, the physics of nanodevices is studied with the goal to apply them in the semiconductor industry. Miniaturization of device dimensions towards the nanoscale can offer clear advantages in terms of operation speed, device density and sensitivity.
Organic molecules are important components of future functional nanostructures. Some of the most important techniques used in studies of single organic molecules have originated from Casimir research groups, notably the mechanically controllable break junction technique. Current research focuses for example on interference effects of multiple current paths in the molecules, which may be relevant for efficient thermo-electric energy conversion, or current-induced non-conservative forces, which could allow electrically driven motion at the nanoscale.
Scanning-probe microscopy: Casimir researchers in Leiden are pioneering magnetic resonance force microscopy, a new type of scanning probe that measures local magnetic forces in combination with magnetic resonance. Its sensitivity has now been refined to the point that the magnetic force due to a single electron spin can be detected. Advances in this area will have impact on medical imaging techniques as well as fundamental biophysical studies of complex molecules such as proteins. Other groups focus on the formation of magnetism on the scale of individual atoms. Using low-temperature STM one can address single magnetic atoms deposited onto a metal surface and visualize their spin states through inelastic electron tunneling spectroscopy. It is even possible to move the atoms around so as to build artificial 'molecules' atom-by-atom, optimizing their magnetic properties for scientific and technological objectives.
