Origin of Distinct Insulating Domains in the Layered Charge Density Wave Material 1T-TaS2

Abstract

Vertical charge order shapes the electronic properties in layered charge density wave (CDW) materials. Various stacking orders inevitably create nanoscale domains with distinct electronic structures inaccessible to bulk probes. Here, the stacking characteristics of bulk 1$T$-TaS$2$ are analyzed using scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations. It is observed that Mott-insulating domains undergo a transition to band-insulating domains restoring vertical dimerization of the CDWs. Furthermore, STS measurements covering a wide terrace reveal two distinct band insulating domains differentiated by band edge broadening. These DFT calculations reveal that the Mott insulating layers preferably reside on the subsurface, forming broader band edges in the neighboring band insulating layers. Ultimately, buried Mott insulating layers believed to harbor the quantum spin liquid phase are identified. These results resolve persistent issues regarding vertical charge order in 1$T$-TaS$2$, providing a new perspective for investigating emergent quantum phenomena in layered CDW materials.

26 pages and 13 figures

References in corpus (5)

• Gate-tunable Phase Transitions in 1T-TaS${}_2$
• Band insulator to Mott insulator transition in 1T-TaS${}_2$
• Correlated electronic states at domain walls of a Mott-charge-density-wave insulator 1T-TaS2
• Pressure dependence of the charge density wave in 1T-TaS2 and its relation to superconductivity
• Origin of Distinct Insulating Domains in the Layered Charge Density Wave Material 1T-TaS2

Cited by in corpus (4)

• Charge ordered phases in the hole-doped triangular Mott insulator 4Hb-TaS2
• Origin of Distinct Insulating Domains in the Layered Charge Density Wave Material 1T-TaS2
• Interlayer Hopping between Surface Mott Insulator and Bulk Band Insulator in layered 1T-TaS_{2}
• Topical review: the nature of the ground state and possibility of a quantum spin liquid in 1T metal dichalcogenides