Flat bands appear in buckled graphene superlattices
Points to note…
+ An international team led by researchers at Rutgers University in the US has found a way to create “flat” electronic bands – that is, electron states in which there is no relationship between the electrons’ energy and velocity – in graphene simply by causing the material to buckle. This new strategy could be used to produce so-called “superlattice” systems that serve as platforms for exploring the collective behaviour of electrons in strongly-interacting quantum systems. Such behaviour is known to be linked to high-temperature superconductivity, but a complete understanding is still lacking.
As the graphene buckles, a “mountain and valley” landscape forms that electrons in the material experience as pseudo-magnetic fields. “These fields are an electronic illusion, but they act as real magnetic fields,” Andrei explains. The result, she says, is a dramatic change in the material’s electronic properties – including the emergence of flat bands.
+ Flat bands are especially interesting for physicists because electrons become “dispersionless” in these bands – that is, their kinetic energy is suppressed. As the electrons slow down almost to a halt, their effective mass approaches infinity, leading to exotic topological phenomena as well as strongly-correlated states of matter associated with high-temperature superconductivity, magnetism and other quantum properties of solids.
+ According to the team, the new technique could thus become a general strategy for creating other superlattice systems and using them to explore interaction phenomena characteristic of flat bands.+ The researchers, who report their work in Nature, say they would now like to develop ways of engineering buckled 2D materials with novel electronic and mechanical properties for use in applications such as nanorobotics and quantum computing.
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