Spectroscopic visualization and phase manipulation of chiral charge density waves in 1T-TaS2

Abstract

The chiral charge density wave is a many-body collective phenomenon in condensed matter that may play a role in unconventional superconductivity and topological physics. Two-dimensional chiral charge density waves provide the building blocks for the fabrication of various stacking structures and chiral homostructures, in which physical properties such as chiral currents and the anomalous Hall effect may emerge. Here, we demonstrate the phase manipulation of two-dimensional chiral charge density waves and the design of in-plane chiral homostructures in 1T-TaS2. We use chiral Raman spectroscopy to directly monitor the chirality switching of the charge density wave—revealing a temperature-mediated reversible chirality switching. We find that interlayer stacking favours homochirality configurations, which is confirmed by first-principles calculations. By exploiting the interlayer chirality-locking effect, we realise in-plane chiral homostructures in 1T-TaS2. Our results provide a versatile way to manipulate chiral collective phases by interlayer coupling in layered van der Waals semiconductors.

Control of Charge‐Spin Interconversion in van der Waals Heterostructures with Chiral Charge Density Waves

“…However, this scale is much smaller than our micrometer‐level devices. Although nanometer‐ and millimeter‐size chiral domains have been reported in recent studies, [ 36,48,49 ] the size could also be restricted by the appearance of impurities. [ 40 ] Therefore, we deduce that the contributions from UREE and interfacial $$\sigma _{xy}^y$$ are canceled out due to the mixed chiral domains with opposite handedness, that is, the vanishing $$R_{{\mathrm{CSI}}}^{{S}_y}$$ in our experiments, whereas the conventional REE and interfacial $$\sigma _{xy}^x$$ contribute to the observed $$R_{{\mathrm{CSI}}}^{{S}_x}$$.…”

Chiral Stacking Identification of Two-Dimensional Triclinic Crystals Enabled by Machine Learning

“…Taking chiral molecules as examples, the solution with both enantiomers in equal amounts, known as a racemic mixture (RM), is optically inactive and has negligible chiroptical response; while a solution with an unequal amount of enantiomers normally preserves optical activity, which can be roughly treated as the superposition of an optically inactive racemic mixture and the optically active enantiomerically pure (EP) remainder . Recently, a few two-dimensional (2D) layered crystals including ReS 2 , ReSe 2 , − and 1T-TaS 2 − are reported to have 2D planar chirality, which present numerous chiral properties such as chiral charge density wave order, , enantiomer-dependent second harmonic generation (SHG), and linear polarized Raman , response, as well as quantum interference-directed chiral Raman scattering . Although these materials are achiral in three-dimensional space, they are usually confined to a substrate (xy-plane) and are therefore nonsuperimposable on their 2 D enantiomers by any rotation about the axis perpendicular to the plane [see the example of monolayer (1L) ReX 2 (X = S or Se) in Figure a].…”

Controllable Growth of 2D V3S5 Single Crystal by Chemical Vapor Deposition

“…Atomic structure engineering of 2D transition metal chalcogenides (TMCs) provides a promising platform to achieve attractive properties, which include superconductivity, interlayer exciton, magnetism, charge-density waves (CDWs), and so on. [1][2][3][4] In order to control and manipulate the atomic structures of 2D TMCs, various methods have been explored, such as ion intercalation, alloying, strain, and electric field. [5][6][7][8] Among these strategies, intercalation method is regarded as an effective way to introduce novel physical properties that do not DOI: 10.1002/adfm.202308356 exist in intrinsic materials due to the tuned electronic structures.…”

“…Atomic structure engineering of 2D transition metal chalcogenides (TMCs) provides a promising platform to achieve attractive properties, which include superconductivity, interlayer exciton, magnetism, charge‐density waves (CDWs), and so on. [ 1–4 ] In order to control and manipulate the atomic structures of 2D TMCs, various methods have been explored, such as ion intercalation, alloying, strain, and electric field. [ 5–8 ]…”