The ordinary graphite in pencil lead is proving to be surprisingly multifaceted at the microscale.
In a study appearing today in the journal Nature, MIT researchers report that a certain microscopic structure found in natural graphite can host multiple superconducting states. Superconductivity is an electronic state of matter in which electrons pair up and glide through a material with zero resistance.
While there are thousands of materials that are known to be superconductors, it is rare for one material to host multiple forms of superconductivity.
The researchers discovered the multiple superconducting states in atomically thin exfoliations of graphite, known as graphene. Specifically, graphene is a single-atom-thin sheet of carbon atoms arranged precisely in a microscopic lattice. The team made its discoveries in samples of rhombohedral graphene, which is a natural structure within graphite consisting of a stack of four or five graphene layers.
Interestingly, the researchers found that several of the new superconducting states in rhombohedral graphene are able to persist in the presence of a magnetic field, which normally kills superconductivity.
And in a further surprise, these superconducting states even get stronger when exposed to a magnetic field.
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