2022 New's Items

Topological quantum interference in a pumped Su-Schrieffer-Heeger lattice

Li Z
Atalaya J
Whaley KB
2022

Topological quantum interference emerges from the interplay between quantum mechanics and topology. We present evidence for two types of such interference phenomenon that can result from the quantum dynamics of initial topological states. We realize both types of topological quantum interference in a pumped non-Hermitian Su-Schrieffer-Heeger lattice that can be implemented by creation and coherent control of excitonic states of trapped neutral atoms. On quenching the system from the topological to the gapless phases and then back again, we find that interference patterns develop in...

Interplay of vibration- and environment-assisted energy transfer

Li Z
Ko L
Yang Z
Sarovar M
Whaley KB
2022

We study the interplay between two environmental influences on excited state energy transfer in photosynthetic light harvesting complexes, namely, vibrationally assisted energy transfer (VAET) and environment-assisted quantum transport (ENAQT), considering a dimeric chromophore donor–acceptor model as a prototype for larger systems. We demonstrate how the basic features of the excitonic energy transfer are influenced by these two environments, both separately and together, with the environment being fully quantum in the case of VAET and treated in the Haken–Strobl–Reineker classical...

Spectroscopy signatures of electron correlations in a trilayer graphene/hBN moiré superlattice

Yang J
Zhang Y
Chen G
Han T
Zhang Q
Zhang Y
Wang FC
Ju Lu
2022

ABC-stacked trilayer graphene/hexagonal boron nitride moiré superlattice (TLG/hBN) has emerged as a playground for correlated electron physics. We report spectroscopy measurements of dual-gated TLG/hBN using Fourier transform infrared photocurrent spectroscopy. We observed a strong optical transition between moiré minibands that narrows continuously as a bandgap is opened by gating, indicating a reduction of the single-particle bandwidth. At half-filling of the valence flat band, a broad absorption peak emerges at ~18 milli–electron volts, indicating direct optical excitation across...

Emerging exciton physics in transition metal dichalcogenide heterobilayers

Regan EC
Wang D
Paik EY
MacDonald AH
Deng H
Wang FC
2022

Atomically thin transition metal dichalcogenides (TMDs) are 2D semiconductors with tightly bound excitons and correspondingly strong light–matter interactions. Owing to the weak van der Waals bonding between layers, TMDs can be isolated and stacked together to form synthetic heterostructures with emergent electronic and excitonic properties. In this Review, we focus on the emergent exciton physics in moiré superlattices and in TMD heterobilayers coupled to optical cavities, where exciton behaviour can be dramatically modified by the environment. In moiré superlattices, a small twist...

Correlated interlayer exciton insulator in heterostructures of monolayer WSe2 and moiré WS2/WSe2

Zhang Z
Regan EC
Wang D
Zettl A
Zaletel MP
Wang FC
2022

Moiré superlattices in van der Waals heterostructures have emerged as a powerful tool for engineering quantum phenomena. Here we report the observation of a correlated interlayer exciton insulator in a double-layer heterostructure composed of a WSe2 monolayer and a WS2/WSe2 moiré bilayer that are separated by ultrathin hexagonal boron nitride. The moiré WS2/WSe2 bilayer features a Mott insulator state when the density of holes is one per moiré lattice site...

Intralayer charge-transfer moiré excitons in van der Waals superlattices

Naik MH
Regan EC
Zhang Z
Chan YH
Wang F
Louie SG
2022

Moiré patterns of transition metal dichalcogenide heterobilayers have proved to be an ideal platform on which to host unusual correlated electronic phases, emerging magnetism and correlated exciton physics. Whereas the existence of new moiré excitonic states is established1,...

Charge Transfer Dynamics in MoSe2/hBN/WSe2 Heterostructures

Yoon Y
Zhang Z
Qi R
Joe AY
Sailus R
Watanabe K
Taniguchi T
Tongay S
Wang F
2022

Ultrafast charge transfer processes provide a facile way to create interlayer excitons in directly contacted transition metal dichalcogenide (TMD) layers. More sophisticated heterostructures composed of TMD/hBN/TMD enable new ways to control interlayer exciton properties and achieve novel exciton phenomena, such as exciton insulators and condensates, where longer lifetimes are desired. In this work, we experimentally study the charge transfer dynamics in a heterostructure composed of a 1 nm thick hBN spacer between MoSe2 and WSe2...

Big Data in a Nano World: A Review on Computational, Data-Driven Design of Nanomaterials Structures, Properties, and Synthesis

Yang RX
McCandler CA
Andriuc O
Siron M
Woods-Robinson R
Horton MK
Persson KA
2022

The recent rise of computational, data-driven research has significant potential to accelerate materials discovery. Automated workflows and materials databases are being rapidly developed, contributing to high-throughput data of bulk materials that are growing in quantity and complexity, allowing for correlation between structural–chemical features and functional properties. In contrast, computational data-driven approaches are still relatively rare for nanomaterials discovery due to the rapid scaling of computational cost for finite systems. However, the distinct behaviors at the...

Exploring the Morphotropic Phase Boundary in Epitaxial PbHf1–xTixO3 Thin Films

Acharya M
Ling H
Lou D
Ramesh M
Hanrahan B
Velarde G
Asta M
Persson KA
Martin LW
2022

Epitaxial PbHf1–xTixO3/SrTiO3(001) thin-film heterostructures are studied for a potential morphotropic phase boundary (MPB) akin to that in the PbZr1–xTixO3 system. End members, PbHfO3 and PbTiO3, were found to possess orthorhombic (Pbam) and tetragonal (P4mm) crystal structures and antiferroelectric and...