Related topics: electrons · atoms · molecules

Magnetic 'hedgehogs' could store big data in a small space

Atomic-scale magnetic patterns resembling a hedgehog's spikes could result in hard disks with massively larger capacities than today's devices, a new study suggests. The finding could help data centers keep up with the exponentially ...

Unmasking the magic of superconductivity in twisted graphene

The discovery in 2018 of superconductivity in two single-atom-thick layers of graphene stacked at a precise angle of 1.1 degrees (called 'magic'-angle twisted bilayer graphene) came as a big surprise to the scientific community. ...

Tracking topological conditions in graphene

Scientists have been able to demonstrate that graphene nanostructures can be generated by annealing of a nanostructured silicon carbide crystal for a few years. "These two-dimensional, spatially strongly restricted carbon ...

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Scanning tunneling microscope

Scanning tunneling microscopy (STM) is a powerful technique for viewing surfaces at the atomic level. Its development in 1981 earned its inventors, Gerd Binnig and Heinrich Rohrer (at IBM Zürich), the Nobel Prize in Physics in 1986. STM probes the density of states of a material using tunneling current. For STM, good resolution is considered to be 0.1 nm lateral resolution and 0.01 nm depth resolution. The STM can be used not only in ultra high vacuum but also in air and various other liquid or gas ambients, and at temperatures ranging from near zero kelvin to a few hundred degrees Celsius.

The STM is based on the concept of quantum tunnelling. When a conducting tip is brought very near to a metallic or semiconducting surface, a bias between the two can allow electrons to tunnel through the vacuum between them. For low voltages, this tunneling current is a function of the local density of states (LDOS) at the Fermi level, Ef, of the sample. Variations in current as the probe passes over the surface are translated into an image. STM can be a challenging technique, as it requires extremely clean surfaces and sharp tips.

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