| Project Detail |
Understanding high-temperature superconductivity in cuprates is arguably the hardest problem in condensed matter. Active research in the pastten years has shown that a successful microscopic theory of superconductivity will need to describe other electronic phases that emerge alongside superconductivity. One of those electronic phases are charge-density waves (CDWs). We propose a novel approach to study CDWs and their competition with superconductivity down to the atomic scale using Transmission Electron Microscopy (TEM) and ultrafast TEM (UTEM) at cryogenic temperatures in the particularly clean cuprate YBa2Cu3Oy. These techniques are very sensitive to the periodic lattice distortion (PLD) that results from the coupling between the CDW and the lattice. Being able to study CDWs at the atomic scale, we will achieve a complete picture of the CDW properties in real-space that goes beyond what has been uncovered by X-ray diffraction and Nuclear Magnetic Resonance (NMR).
Firstly, this will allow to study whether CDWs are correlated with disorder or vice versa.
Secondly, by applying uniaxial strain we will enter the long-range CDW phase and investigate whether the PLD is truly incommensurate or whether repeated discommensurations shift the CDW wave vector away from a commensurate value, as has been suggested by NMR.
Thirdly, using UTEM and photo-excitation within the superconducting state we will have the chance to observe the competition of CDWs with superconductivity in real-space at the femtosecond time scale.
Before studying YBa2Cu3Oy, we will investigate a CDW model system, the transition metal trichalcogenide ErTe3.
These two materials have a number of similarities. Both these studies will advance the understanding of charge-density waves. This novel approach will establish the study of charge ordering using electron microscopy at croygenic temperatures in cuprate superconductors. |
