Phys.org March 1, 2024 Charge density waves are emergent quantum states that spontaneously reduce crystal symmetry, drive metal-insulator transitions, and precede superconductivity. In low-dimensions, distinct quantum states arise, however, thermal fluctuations and external disorder destroy long-range order. A team of researchers in the US (University of Michigan, Harvard University) has stabilized ordered 2D charge density waves through endotaxial synthesis of confined monolayers of 1T-TaS2. Specifically, an ordered incommensurate charge density wave (oIC-CDW) was realized in 2D with dramatically enhanced amplitude and resistivity. By enhancing CDW order, the hexatic nature of charge density waves became observable. Upon heating via in-situ TEM, […]
Tag Archives: Charge density wave
Ringing an electronic wave: Elusive massive phason observed in a charge density wave
Phys.org March 9, 2023 The lowest-lying fundamental excitation of an incommensurate charge-density-wave material is believed to be a massless phason—a collective modulation of the phase of the charge-density-wave order parameter. However, long-range Coulomb interactions should push the phason energy up to the plasma energy of the charge-density-wave condensate, resulting in a massive phason and fully gapped spectrum. A team of researchers in the US (University of Illinois, SLAC National Accelerator Laboratory) used time-domain terahertz emission spectroscopy, to investigate this issue in (TaSe4)2I, a quasi-one-dimensional charge-density-wave insulator. On transient photoexcitation at low temperatures, they found the material strikingly emits coherent, narrowband […]