Researchers Paula Mellado, Francisco Muñoz, and Javiera Cabezas-Escares from the Universidad de Chile have published a study in the journal Physical Review B that explores the mechanisms behind the onset of incommensurate charge order in layered materials. Their work focuses on a specific type of charge density wave, known as an incommensurate charge density wave, which is a periodic modulation of charge that breaks translational symmetry at a momentum that does not coincide with the primitive lattice vectors. The researchers studied a half-filled, four-band tight-binding model on a ladder with a relative shift between the legs, induced by the dimerization of one of them.
The shift results in a moiré supercell comprising multiple composite cells and a modulated inter-leg tunneling. The moiré potential compresses the leg bands into flat minibands near the Fermi level, resulting in additional low-energy peaks in the density of states. Including Coulomb interactions, the researchers found an incommensurate charge-density-wave phase in which the charge modulation is out of phase between the legs. The collective excitations of this state are long-lived neutral, acoustic phasons whose speed is controlled by the moiré parameter and the inter-leg tunneling amplitude.
The study sheds light on the role of interlayer incongruities in the formation of excitonic charge-ordered phases in van der Waals and heterostructured materials. This research could have practical applications in the energy sector, particularly in the development of advanced materials for energy storage and conversion devices. By understanding the mechanisms behind charge order in layered materials, researchers can potentially design materials with enhanced properties for use in batteries, supercapacitors, and other energy technologies.
The research was published in the journal Physical Review B, a peer-reviewed scientific journal that covers research on condensed matter and materials physics. The study provides valuable insights into the fundamental physics of charge order in layered materials, which could have significant implications for the development of next-generation energy technologies.
This article is based on research available at arXiv.