The shifting, scintillating pattern you can see when you stack two slightly misaligned window screens is called moiré. A similar interference effect occurs when scientists stack two-dimensional crystals with mismatched atomic spacings. Moiré superlattices display exotic physical properties that are absent in the layers that make up the patterns. These properties are rooted in the quantum nature of electrons.
Researchers have discovered a new property in the moiré superlattices formed in crystals made of tungsten diselenide/tungsten disulfide(WSe2/WS2). In these two-dimensional crystals, the interactions between electrons become so strong that electrons "freeze" and form an ordered array.
WSe2/WS2 moiré superlattices turn out to be an optimal playground for tuning the interactions between electrons. The stronger these interactions, the more prominent the quantum mechanical nature of solid materials. This allows exotic states of matter like unconventional superconductivity to form.
Researchers used lasers to "observe" the electron motion without the artifacts that plague other measurement techniques. They uncovered a rare quantum state of matter, never before observed in moiré superlattices. Understanding and controlling the quantum motion of electrons will allow scientists to build microelectronic devices of the future and robust qubits for quantum computing.
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