Topological Vortices vs. discommensuration dislocations in charge-density-wave 2H-TaSe2

ORAL

Abstract

Charge density wave (CDW) discommensuration (DC) refers to a boundary between two different CDW phases and is a key to understand the phase transition from commensurate to incommensurate CDW. The phase transition can be rendered as a process of creating or eliminating DCs that results in change of incommensurability, and the place of such process, where DCs merge to each other, has been known as CDW dislocation. The idea of CDW DC dislocation has been primarily studied in 2H-TaSe2, which shows a clear phase transition from incommensurate to commensurate CDW. Although there have been several experimental and theoretical results supporting the idea, it has nevertheless not been verified at the atomic scale using, for example, scanning tunneling microscopy (STM). We present an observation of such entangled points of multiple DCs in 2H-TaSe2 by STM. The observation showed no phase slip which is against the idea of CDW dislocation, but the result instead unveiled the formation of topological vortices. In this talk an atomic scale comparison among the CDW DC dislocation model, the experimental results as well as a complicated vortex-like domain topology of 2H-TaSe2 will be presented.

–

Presenters

  • Seong Joon Lim

    Rutgers University, New Brunswick, Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ

Authors

  • Seong Joon Lim

    Rutgers University, New Brunswick, Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ

  • Choong-Jae Won

    Max Planck POSTECH/Korea Research Initiative, Pohang University of Science and Technology, Laboratory for Pohang Emergent Materials, Pohang Accelerator Laboratory and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science and Technology,

  • Sang-Wook Cheong

    Rutgers University, Department of Physics and Astronomy, Rutgers University, Rutgers University, New Brunswick, Rutgers Center for Emergent Materials and Department of Physics & Astronomy, Rutgers University, Center for Quantum Materials Synthesis and Department of Physics and Astronomy, Rutgers, the State University of New Jersey, Department of Physics, Rutgers University, Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA, Physics, Rutgers University, Physics and Astronomy, Rutgers University, New Brunswick, Department of Physics and Astronomy, Rutgers University, New Jersey, Rutgers University, Physics and Astronomy, and Laboratory for Pohang Emergent Materials and Max Plank POSTECH Center for Complex Phase Materials, Pohang University of Science, RCEM, Department of Physics and Astronomy, Rutgers U., Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Department of Physics and Astronomy, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA, Rutgers Center for Emergent Materials