ORCID Profile
0000-0001-9144-4368
Current Organisations
University of California, San Diego
,
Central South University
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Physical Oceanography | Glaciology | Climate Change Processes | Oceanography
Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) | Expanding Knowledge in the Environmental Sciences | Expanding Knowledge in the Earth Sciences |
Publisher: American Meteorological Society
Date: 08-2021
Publisher: Springer Science and Business Media LLC
Date: 07-02-2017
Publisher: American Geophysical Union (AGU)
Date: 28-05-2018
DOI: 10.1029/2017GL076909
Publisher: Research Square Platform LLC
Date: 15-05-2023
DOI: 10.21203/RS.3.RS-2774598/V1
Abstract: Moiré superlattices are formed by stacking 2D materials with a twist angle and have recently gained attention as a platform for investigating the interactions and correlations of moiré-trapped interlayer excitons (IXs). However, understanding these excitons remains challenging, as theoretical predictions suggest the existence of both parallel and antiparallel dipole-dipole interactions, while only repulsive interactions with a parallel configuration have been experimentally observed. Here, we investigate the localization of strain-induced moiré interlayer excitons in twisted transition metal dichalcogenide (TMDC) superlattices. Our results reveal that modulating the moiré trap in strain-engineered homobilayers leads to a higher density and emission efficiency of IXs, while also enhancing dipole-dipole interactions. In particular, we observe a transition in the nature of the moiré interlayer exciton-dipole interaction from repulsion to attraction in a twist-angle homostructure, resulting in a stable interlayer biexciton (IXX) phase with an antiparallel configuration, which had only been theoretically predicted before. Moreover, the moiré trap in homobilayers can be modulated by adjusting the spacing of the Au nanoarrays, which enabled us to achieve IXX emission up to 150 K, the highest temperature reported to date. This breakthrough is expected to pave the way for the observation of a Bose-Einstein condensate at room temperature. Our findings provide new opportunities for studying correlated many-body systems and have implications for developing novel optoelectronic devices and controllable nonlinear optics.
Publisher: AIP Publishing
Date: 12-10-2020
DOI: 10.1063/5.0015431
Abstract: The excitonic effects in two-dimensional transition metal dichalcogenides and their heterostructures have been extensively investigated. Significantly, the moiré excitons, induced by a moiré superlattice in a twisted heterostructure, have triggered tremendous attention, demonstrating the practicability of artificial excitonic crystals. Besides, recent works have shown that the excitonic states in homostructures also exhibit novel properties worthy of further development. Here, we present a tear-and-stack technique for fabricating a regular or a twisted homostructure. Such a strategy was utilized to reassemble a monolayer WSe2 into a twisted homostructure, and various excitons from this structure have been identified in the photoluminescence spectra. Interestingly, the unusual equidistant splitting was first observed in the defect-bound excitons. It is believed that this phenomenon is attributed to the various defect states and the local stacking patterns. This interpretation is supported by theoretical calculations, which show the dependence of the energy band structure on different defect states and local stacking patterns. These unconventional defect-bound excitons are key building blocks in the research of homostructures that highlight the feasibility of artificially manipulating local excitons for practical applications.
Publisher: Springer Science and Business Media LLC
Date: 17-02-2021
DOI: 10.1038/S41467-021-21267-4
Abstract: Nonlinear optical effects in layered two-dimensional transition metal chalcogenides have been extensively explored recently because of the promising prospect of the nonlinear optical effects for various optoelectronic applications. However, these materials possess sizable bandgaps ranging from visible to ultraviolet region, so the investigation of narrow-bandgap materials remains deficient. Here, we report our comprehensive study on the nonlinear optical processes in palladium diselenide (PdSe 2 ) that has a near-infrared bandgap. Interestingly, this material exhibits a unique thickness-dependent second harmonic generation feature, which is in contrast to other transition metal chalcogenides. Furthermore, the two-photon absorption coefficients of 1–3 layer PdSe 2 ( β ~ 4.16 × 10 5 , 2.58 × 10 5 , and 1.51 × 10 5 cm GW −1 ) are larger by two and three orders of magnitude than that of the conventional two-dimensional materials, and giant modulation depths ( α s ~ 32%, 27%, and 24%) were obtained in 1–3 layer PdSe 2 . Such unique nonlinear optical characteristics make PdSe 2 a potential candidate for technological innovations in nonlinear optoelectronic devices.
Publisher: Research Square Platform LLC
Date: 11-08-2023
DOI: 10.21203/RS.3.RS-3245746/V1
Abstract: Moiré-trapped interlayer excitons within two-dimensional (2D) moiré superlattices offer a remarkably versatile and adaptable platform, enabling an extensive exploration of dipole interactions and many-body correlations in the realm of 2D quantum systems. Conversely, optical microcavities, capable of confining photons within a confined space, profoundly lify the interplay between light and matter, ushering in a new era of possibilities for photonics research. However, the intricate synergy between moiré potential and optical microcavities remains shrouded in uncertainty. Here, we present a precise integration of a twisted WSe2/WSe2 homobilayer with an optical microcavity, forging a cooperative alliance between moiré excitons and microcavity photons. Our investigation unveils highly localized moiré-enhanced emission in the suspended WSe2/WSe2 homobilayer, distinguished by remarkably sharp emission lines with peak widths reduced by a factor of three, alongside distinctive valleytronic attributes. Notably, our pioneering work uncovers a profound transformation in the nature of moiré exciton-dipole interactions within the suspended twist-angle WSe2/WSe2 homobilayer. This transformation triggers an unprecedented shift from repulsive to attractive interactions, culminating in the emergence of a robust moiré biexciton phase—an occurrence previously confined to theoretical predictions. Our findings provide essential insights into the cooperative interplay between moiré excitons and optical microcavities, illuminating the underlying physics and charting a course for future research and technological advancements in this captivating realm.
Publisher: Springer Science and Business Media LLC
Date: 06-2022
DOI: 10.1038/S41377-022-00854-0
Abstract: Recent advances in twisted van der Waals heterostructure superlattices have emerged as a powerful and attractive platform for exploring novel condensed matter physics due to the interplay between the moiré potential and Coulomb interactions. The moiré superlattices act as a periodic confinement potential in space to capture interlayer excitons (IXs), resulting in moiré exciton arrays, which provide opportunities for quantum emitters and many-body physics. The observation of moiré IXs in twisted transition-metal dichalcogenide (TMD) heterostructures has recently been widely reported. However, the capture and study of the moiré intralayer excitons based on TMD twisted homobilayer (T-HB) remain elusive. Here, we report the observation of moiré intralayer excitons in a WSe 2 /WSe 2 T-HB with a small twist angle by measuring PL spectrum. The multiple split peaks with an energy range of 1.55–1.73 eV are different from that of the monolayer WSe 2 exciton peaks. The split peaks were caused by the trapping of intralayer excitons via the moiré potential. The confinement effect of the moiré potential on the moiré intralayer excitons was further demonstrated by the changing of temperature, laser power, and valley polarization. Our findings provide a new avenue for exploring new correlated quantum phenomena and their applications.
Publisher: Research Square Platform LLC
Date: 14-09-2022
DOI: 10.21203/RS.3.RS-2037324/V1
Abstract: Moiré superlattice created by the stacking of twisted 2D layered materials have become a new platform for the study of quantum optics. The strong coupling of moiré superlattices can generate flat minibands that enhance electronic interactions and produce a variety of fascinating strongly correlated states such as non-conventional superconductivity, Mott insulating states and moiré excitons. However, the influence between the adjustment and localization of moiré excitons in Van der Waals heterostructures has not been the subject of experimental investigations. Here we report experimental evidence of the localization-enhanced moiré excitons in the twisted WSe2/WS2/WSe2 heterotrilayer with type-II band alignments. At low temperature, we observed multiple excitons splitting phenomena in the twisted WSe2/WS2/WSe2 heterotrilayer, manifesting as multiple sharp emission lines, contrasting strongly with the moiré excitonic behavior of the twisted WSe2/WS2 heterobilayer (the linewidth is 4 times narrower). This is primarily because the enhancement of the two moiré potentials in the twisted heterotrilayer enables the moiré excitons at the highly localized interface. Furthermore, the changes in temperature, laser power and valley polarization further demonstrate the confinement effect of moiré potential on moiré excitons. Our findings provide a new way for the localization of moiré excitons in twist-angle heterostructures, facilitating the development of coherent quantum light emitters.
Publisher: American Geophysical Union (AGU)
Date: 08-2019
DOI: 10.1029/2019JC015162
Publisher: Springer Science and Business Media LLC
Date: 25-07-2013
Abstract: We report a systematic investigation of the temperature dependence of electrical resistance behaviours in tri- and four-layer graphene interconnects. Nonlinear current–voltage characteristics were observed at different temperatures, which are attributed to the heating effect. With the resistance curve derivative analysis method, our experimental results suggest that Coulomb interactions play an essential role in our devices. The room temperature measurements further indicate that the graphene layers exhibit the characteristics of semiconductors mainly due to the Coulomb scattering effects. By combining the Coulomb and short-range scattering theory, we derive an analytical model to explain the temperature dependence of the resistance, which agrees well with the experimental results.
Publisher: American Meteorological Society
Date: 08-2020
DOI: 10.1175/JTECH-D-19-0203.1
Abstract: Proposals from multiple nations to deploy air–sea flux moorings in the Southern Ocean have raised the question of how to optimize the placement of these moorings in order to maximize their utility, both as contributors to the network of observations assimilated in numerical weather prediction and also as a means to study a broad range of processes driving air–sea fluxes. This study, developed as a contribution to the Southern Ocean Observing System (SOOS), proposes criteria that can be used to determine mooring siting to obtain best estimates of net air–sea heat flux ( Q net ). Flux moorings are envisioned as one component of a multiplatform observing system, providing valuable in situ point time series measurements to be used alongside satellite data and observations from autonomous platforms and ships. Assimilating models (e.g., numerical weather prediction and reanalysis products) then offer the ability to synthesize the observing system and map properties between observations. This paper develops a framework for designing mooring array configurations to maximize the independence and utility of observations. As a test case, within the meridional band from 35° to 65°S we select eight mooring sites optimized to explain the largest fraction of the total variance (and thus to ensure the least variance of residual components) in the area south of 20°S. Results yield different optimal mooring sites for low-frequency interannual heat fluxes compared with higher-frequency subseasonal fluxes. With eight moorings, we could explain a maximum of 24.6% of high-frequency Q net variability or 44.7% of low-frequency Q net variability.
Publisher: Research Square Platform LLC
Date: 28-07-2020
DOI: 10.21203/RS.3.RS-38019/V1
Abstract: Nonlinear optical (NLO) effects in layered atomically thin two-dimensional (2D) materials provide a promising prospect for multifarious optoelectronic applications. The NLO characteristics of transition metal chalcogenides (TMDCs) are attracting growing attention and have been extensively explored recently. However, these materials possess sizable bandgaps ranging from visible to ultraviolet regions, so the investigation of narrow-bandgap materials remains deficient. Here, we report our comprehensive study on the NLO processes in palladium diselenide (PdSe2) flakes that have a near-infrared bandgap. Interestingly, this material exhibits a unique thickness-dependent second harmonic generation (SHG) feature, embodied in the strong (negligible) SHG signals in even (odd) layers, in contrast with that of other TMDCs. Furthermore, the two-photon absorption (TPA) coefficients (β ~4.5×105, 2.83×105, 1.7×105, and 1.85×104 cm/GW) of 1-3 L and bulk PdSe2 are larger by two and three orders of magnitude, compared with that of the conventional 2D materials. Significantly, at the excitation wavelength of 600 nm, a robust saturable absorption with giant modulation depths (αs ~47%, 30%, and 41%) was observed in 1-3 L PdSe2, which has yet been obtained in other 2D materials. Such unique NLO characteristics enable PdSe2 to be a potential candidate for technological innovations in nonlinear optoelectronic devices.
Publisher: Springer Science and Business Media LLC
Date: 12-05-2023
DOI: 10.1038/S41377-023-01171-W
Abstract: The stacking of twisted two-dimensional (2D) layered materials has led to the creation of moiré superlattices, which have become a new platform for the study of quantum optics. The strong coupling of moiré superlattices can result in flat minibands that boost electronic interactions and generate interesting strongly correlated states, including unconventional superconductivity, Mott insulating states, and moiré excitons. However, the impact of adjusting and localizing moiré excitons in Van der Waals heterostructures has yet to be explored experimentally. Here, we present experimental evidence of the localization-enhanced moiré excitons in the twisted WSe 2 /WS 2 /WSe 2 heterotrilayer with type-II band alignments. At low temperatures, we observed multiple excitons splitting in the twisted WSe 2 /WS 2 /WSe 2 heterotrilayer, which is manifested as multiple sharp emission lines, in stark contrast to the moiré excitonic behavior of the twisted WSe 2 /WS 2 heterobilayer (which has a linewidth 4 times wider). This is due to the enhancement of the two moiré potentials in the twisted heterotrilayer, enabling highly localized moiré excitons at the interface. The confinement effect of moiré potential on moiré excitons is further demonstrated by changes in temperature, laser power, and valley polarization. Our findings offer a new approach for localizing moiré excitons in twist-angle heterostructures, which has the potential for the development of coherent quantum light emitters.
Publisher: American Meteorological Society
Date: 28-03-2012
DOI: 10.1175/JCLI-D-11-00203.1
Abstract: The boreal winter response of the ocean mixed layer to the Madden–Julian oscillation (MJO) in the Indo-Pacific region is determined using in situ observations from the Argo profiling float dataset. Composite averages over numerous events reveal that the MJO forces systematic variations in mixed layer depth and temperature throughout the domain. Strong MJO mixed layer depth anomalies (& m peak to peak) are observed in the central Indian Ocean and in the far western Pacific Ocean. The strongest mixed layer temperature variations (& .6°C peak to peak) are found in the central Indian Ocean and in the region between northwest Australia and Java. A heat budget analysis is used to evaluate which processes are responsible for mixed layer temperature variations at MJO time scales. Though uncertainties in the heat budget are on the same order as the temperature trend, the analysis nonetheless demonstrates that mixed layer temperature variations associated with the canonical MJO are driven largely by anomalous net surface heat flux. Net heat flux is dominated by anomalies in shortwave and latent heat fluxes, the relative importance of which varies between active and suppressed MJO conditions. Additionally, rapid deepening of the mixed layer in the central Indian Ocean during the onset of active MJO conditions induces significant basin-wide entrainment cooling. In the central equatorial Indian Ocean, MJO-induced variations in mixed layer depth can modulate net surface heat flux, and therefore mixed layer temperature variations, by up to ~40%. This highlights the importance of correctly representing intraseasonal mixed layer depth variations in climate models in order to accurately simulate mixed layer temperature, and thus air–sea interaction, associated with the MJO.
Publisher: Springer Science and Business Media LLC
Date: 28-09-2016
DOI: 10.1038/NCLIMATE3103
Publisher: American Meteorological Society
Date: 04-2020
Abstract: Wintertime surface ocean heat loss is the key process driving the formation of Subantarctic Mode Water (SAMW), but there are few direct observations of heat fluxes, particularly during winter. The Ocean Observatories Initiative (OOI) Southern Ocean mooring in the southeast Pacific Ocean and the Southern Ocean Flux Station (SOFS) in the southeast Indian Ocean provide the first concurrent, multiyear time series of air–sea fluxes in the Southern Ocean from two key SAMW formation regions. In this work we compare drivers of wintertime heat loss and SAMW formation by comparing air–sea fluxes and mixed layers at these two mooring locations. A gridded Argo product and the ERA5 reanalysis product provide temporal and spatial context for the mooring observations. Turbulent ocean heat loss is on average 1.5 times larger in the southeast Indian (SOFS) than in the southeast Pacific (OOI), with stronger extreme heat flux events in the southeast Indian leading to larger cumulative winter ocean heat loss. Turbulent heat loss events in the southeast Indian (SOFS) occur in two atmospheric regimes (cold air from the south or dry air circulating via the north), while heat loss events in the southeast Pacific (OOI) occur in a single atmospheric regime (cold air from the south). On interannual time scales, wintertime anomalies in net heat flux and mixed layer depth (MLD) are often correlated at the two sites, particularly when wintertime MLDs are anomalously deep. This relationship is part of a larger basin-scale zonal dipole in heat flux and MLD anomalies present in both the Indian and Pacific basins, associated with anomalous meridional atmospheric circulation.
Publisher: Research Square Platform LLC
Date: 11-05-2022
DOI: 10.21203/RS.3.RS-1619289/V1
Abstract: Moiré superlattices in the twisted van der Waals materials have become an excellent platform for exploring new quantum phenomena due to the interaction between atomic structure and electronic correlation. Moiré superlattice can generate periodic moiré potential, which can constrain the recombination of excitons, leading to exotic quantum phenomena, including moiré excitons, flat bands, etc., which have been extensively reported in TMDs structures. However, the effect between the modulating of the moiré potential and the number of twisted layers has not been the subject of experimental research yet. Here we synthesized a twisted trilayer homostructure by a dry-transfer method and the enhancement of the moiré potential by the number of twisted layers is investigated. The moiré potential depths of the twisted bilayer and trilayer homostructure are 111 and 212 meV (increased by 91%), which further demonstrate that the depth of the moiré potential can be controlled by adjusting the number of stacked layers. Enhanced moire potential allows observation of moire excitons at 77 K, which are improved by an order of magnitude bigger than those of other moiré excitons(less than 10 K). Our results provide a new method for controllable preparation of moire potentials and a new avenue for further exploration of highly correlated quantum phenomena.
Publisher: American Geophysical Union (AGU)
Date: 30-06-2022
DOI: 10.1029/2021GB007226
Abstract: The Southern Ocean modulates the climate system by exchanging heat and carbon dioxide (CO 2 ) between the atmosphere and deep ocean. While this region plays an outsized role in the global oceanic anthropogenic carbon uptake, CO 2 is also released to the atmosphere across large swaths of the Antarctic Circumpolar Current (ACC). Southern Ocean outgassing has long been attributed to remineralized carbon from upwelled deep water, but the precise mechanisms by which this water reaches the surface are not well constrained from observations. Using data from a novel array of autonomous biogeochemical profiling floats, we examine Southern Ocean air‐sea CO 2 fluxes and the pathways that transfer carbon from the ocean interior into the mixed layer where air‐sea exchange occurs. These float‐based flux estimates of unprecedented spatial resolution indicate that carbon outgassing occurs predominantly in the Indo‐Pacific sector of the ACC due to variations in the mean surface ocean partial pressure of CO 2 ( p CO 2 ). We show that this zonal asymmetry in surface p CO 2 , and consequently air‐sea carbon fluxes, stems primarily from regional variability in the mixed‐layer entrainment of upwelled carbon‐rich deep water. These results suggest that a sustained circumpolar observing system is crucial to monitor future changes in oceanic carbon release and uptake.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3NR01765F
Abstract: Raman polarization spectra, temperature-dependent photoluminescence (PL), and anisotropic absorption with a linear dichroism transition were studied to gain insights into the physical properties of SiP materials.
Publisher: Springer Science and Business Media LLC
Date: 03-06-2020
DOI: 10.1186/S11671-020-03352-7
Abstract: Graphene has been demonstrated to be a promising material for optoelectronics and photodetection devices because of its ultra-broadband optical absorption and high carrier mobility. However, its integration with optoelectronic systems has been limited by the zero-bandgap and the lack of a gain mechanism. Herein, we demonstrate a novel photodetector based on the graphene nanoribbons (GRNs) with a sizable bandgap. Utilizing trapping charge at the interface between SiO 2 and light-doped silicon, an ultrahigh gain of 22,400 has been obtained. Our devices show an enhanced photoresponsivity (~ 800 AW −1 ) while the response speed is still fast (up to 10 μs). This photoresponsivity is about two orders of magnitude higher compared to that of a previous graphene-based photodetector. The photodetector exhibits a wide-range tunability via source-drain bias and back gate voltage. Our work addresses key challenges for the photodetectors and potentially provides the desired pathway toward practical application of graphene photodetectors that can be externally manipulated by an electric field with fast response speed and high sensitivity.
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0CS01002B
Abstract: Recent advances in moiré superlattices and moiré excitons, such as quantum emission arrays, low-energy flat bands, and Mott insulators, have rapidly attracted attention in the fields of optoelectronics, materials, and energy research.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NR02450K
Abstract: We report observed moiré excitons in the WS 2 /WS 2 T-HS with a twist angle of about 1.5°. Our findings offer a promising prospective for further exploration of artificial excitonic crystals and quantum emitters of TMD moiré patterns.
Publisher: Springer Science and Business Media LLC
Date: 31-08-2021
Location: United States of America
Location: United States of America
Location: United States of America
Start Date: 08-2021
End Date: 12-2027
Amount: $20,000,000.00
Funder: Australian Research Council
View Funded Activity