Moiré Superstructure and Dimensional Crossover of 2D Electronic States on Nanoscale Lead Quantum Films

Abstract

We investigate using scanning tunneling microscopy and spectroscopy electronic aspects of Moiré superstructures in nanoscale Pb quantum films grown on IrTe2, which is a unique layered material with charge-order transitions into stripe phases. Pb ultrathin films exhibit a Moiré superstructure due to the lattice mismatch of Pb and IrTe2, which produces strong lateral electronic modulation of hexagonal symmetry and discreet subbands. Moreover, strongly anisotropic or 1D electronic states are formed in Pb films as modulated by the stripe charge order. Present results indicate the controllability of lateral electronic structures of various ultrathin films by extra interfacial potentials due not only to Moiré superstructures but also to novel electronic orderings of substrates.

Quantum-Confined Electronic States Arising from the Moiré Pattern of MoS2–WSe2 Heterobilayers

“…When two MLs of different 2D materials are combined to form a heterobilayer (or when rotational misalignment occurs between the lattice of MLs of the same 2D material), a moiré pattern will form . Such patterns have been studied in detail, e.g., for graphene on h-BN, − and also for various transition-metal dichalcogenide (TMD) materials. ,,, In a recent report, Zhang et al described scanning tunneling microscopy and spectroscopy (STM–STS) obtained for heterobilayers of MoS 2 and WSe 2 , with the measurements performed at a temperature near 77 K . A moiré corrugation with relatively large amplitude of 0.17 nm (sample bias of +3 V) and a period of 8.7 ± 0.2 nm was observed.…”

Spotlight: Visualization of Moiré Quantum Phenomena in Transition Metal Dichalcogenide with Scanning Tunneling Microscopy

“…In 2017, Hyo Sung Kim et al utilized STM and STS to investigate the moirésuperstructure formed between ultrathin lead (Pb) films and IrTe 2 . 51 They observed a strong lateral electronic modulation in the 2D quantum well states (QWS's) of the Pb films with the same periodicity of the moiréstructure. Specifically, in Pb islands on the hexagonal domain of IrTe 2 , the QWS's were found to split into three distinct sub-bands, each with unique dI/dV lateral patterns and an energy splitting of approximately 120 meV.…”

Twisted van der Waals Quantum Materials: Fundamentals, Tunability, and Applications

“…The STM topography of the IrTe 2 surface at a low temperature shows a coexisting domain of hexagonal and stripe phases in IrTe 2 (Figure a), and the moiré patterns with different periodicity and orientation were observed in both regions The pattern from the Pb film on the hexagonal area gives rise to a regular moiré cell (Figure b), while the pattern from that on the stripe region exhibits a less regular structure (Figure c), owing to the extra strain produced in the hexagonal domain . The induced moiré superlattice leads to a strong lateral modulation in electronic structures of Pb film with split sub-bands on its quantum well states, and the stripe charge ordering from IrTe 2 offers additional tunability and can form 1D electronic states in the ultrathin Pb films . Beyond exploring the moiré effects by stacking atomic layers one on top of the other, starting from the heart of a sandwich structure is expected to open a new way for constructing more possible marvelous phenomena and creating more tenability to materials by decoupling the originally attached materials.…”

“…168 The periodic moirésuperstructures were observed from the structure of Pd/IrTe 2 because of the interfacial lattice mismatch between Pd and IrTe 2 . 215 The STM topography of the IrTe 2 surface at a low temperature shows a coexisting domain of hexagonal and stripe phases in IrTe 2 (Figure 14a), and the moirépatterns with different periodicity and orientation were observed in both regions The pattern from the Pb film on the hexagonal area gives rise to a regular moirécell (Figure 14b), while the pattern from that on the stripe region exhibits a less regular structure (Figure 14c), owing to the extra strain produced in the hexagonal domain. 216 The induced moirésuperlattice leads to a strong lateral modulation in electronic structures of Pb film with split sub-bands on its quantum well states, and the stripe charge ordering from IrTe 2 offers additional tunability and can form 1D electronic states in the ultrathin Pb films.…”

“…216 The induced moirésuperlattice leads to a strong lateral modulation in electronic structures of Pb film with split sub-bands on its quantum well states, and the stripe charge ordering from IrTe 2 offers additional tunability and can form 1D electronic states in the ultrathin Pb films. 215 Beyond exploring the moiréeffects by stacking atomic layers one on top of the other, starting from the heart of a sandwich structure is expected to open a new way for constructing more possible marvelous phenomena and creating more tenability to materials by decoupling the originally attached materials.…”