In superconductors, a collective excitation of Cooper pairs exists which is known as the Higgs mode. If the system is excited out of equilibrium, Higgs oscillations can arise. From these, properties of the superconducting energy gap can be deduced. In conventional superconductors the system oscillates with a frequency corresponding to two times the energy gap. In the case of unconventional superconductors multiple Higgs modes can arise. As a consequence, Higgs oscillations can serve as a spectroscopic method to retrieve information about the symmetry of the energy gap.
Atomically small magnets behave drastically different compared to macroscopic magnets. Quantum mechanical phenomena determine their stability and dynamics. Scanning probe methods can be used to create individual quantum magnets atom by atom. The atomically precise magnetic structures enable the exploration of new concepts for ultra-dense data storage and magnetic sensors for atomic-scale environments.
In transition metal compounds, electrons are strongly entangled (correlated) by Coulomb interaction and forms a rich variety of solid, liquid and gas phases. We are aiming to explore exotic electronic phases formed by spin, charge and orbital degrees of freedom of entangled electrons. In this review, we report that by incorporating relativistic spin-orbit coupling, entanglement of spin and motion of electrons, in complex iridium oxides, even richer phases of correlated electrons emerge including spin orbital electron solid (Mott insulator), Dirac electron gas and Quantum spin liquid.
Graphene, a single atom thick carbon layer, is grown on top of silicon carbide (SiC). When the topmost silicon atoms are sublimated by annealing the SiC substrate, the remaining carbon forms the graphene layer. In order to retrieve the extraordinary electronic properties of the graphene, it must be chemically decoupled from the substrate. This is achieved by inserting hydrogen between graphene and SiC, so-called intercalation, which passivates the substrate. Intercalation of other materials, such as germanium allows to functionalize the graphene, so that a taylor-made doping is possible.
Non-evaporable functional molecules such as proteins and peptides can be converted into intact gas phase ions by electrospray ionization. This allows the deposition on surfaces in a vacuum, and thus the atomically resolving analysis by scanning tunneling microscopy. In addition to a detailed insight into the structure of these large molecules, electrospray ion beam deposition allows steering of the molecular conformation into folded, unfolded or two-dimensionally folded structures.