ORCID Profile
0000-0001-7865-2664
Current Organisations
University of Technology Sydney
,
Monash University
,
GC University Faislabad
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Publisher: American Chemical Society (ACS)
Date: 27-10-2023
Publisher: IOP Publishing
Date: 15-07-2021
Abstract: The Computational 2D Materials Database (C2DB) is a highly curated open database organising a wealth of computed properties for more than 4000 atomically thin two-dimensional (2D) materials. Here we report on new materials and properties that were added to the database since its first release in 2018. The set of new materials comprise several hundred monolayers exfoliated from experimentally known layered bulk materials, (homo)bilayers in various stacking configurations, native point defects in semiconducting monolayers, and chalcogen/halogen Janus monolayers. The new properties include exfoliation energies, Bader charges, spontaneous polarisations, Born charges, infrared polarisabilities, piezoelectric tensors, band topology invariants, exchange couplings, Raman spectra and second harmonic generation spectra. We also describe refinements of the employed material classification schemes, upgrades of the computational methodologies used for property evaluations, as well as significant enhancements of the data documentation and provenance. Finally, we explore the performance of Gaussian process-based regression for efficient prediction of mechanical and electronic materials properties. The combination of open access, detailed documentation, and extremely rich materials property data sets make the C2DB a unique resource that will advance the science of atomically thin materials.
Publisher: Springer Science and Business Media LLC
Date: 04-04-2022
DOI: 10.1038/S41524-022-00730-W
Abstract: Atomically thin two-dimensional (2D) materials are ideal host systems for quantum defects as they offer easier characterisation, manipulation and read-out of defect states as compared to bulk defects. Here we introduce the Quantum Point Defect (QPOD) database with more than 1900 defect systems comprising various charge states of 503 intrinsic point defects (vacancies and antisites) in 82 different 2D semiconductors and insulators. The Atomic Simulation Recipes (ASR) workflow framework was used to perform density functional theory (DFT) calculations of defect formation energies, charge transition levels, Fermi level positions, equilibrium defect and carrier concentrations, transition dipole moments, hyperfine coupling, and zero-field splitting. Excited states and photoluminescence spectra were calculated for selected high-spin defects. In this paper we describe the calculations and workflow behind the QPOD database, present an overview of its content, and discuss some general trends and correlations in the data. We analyse the degree of defect tolerance as well as intrinsic dopability of the host materials and identify promising defects for quantum technological applications. The database is freely available and can be browsed via a web-app interlinked with the Computational 2D Materials Database (C2DB).
Publisher: IOP Publishing
Date: 17-03-2020
Abstract: This report summarizes progress made in understanding properties such as zero-phonon-line energies, emission and absorption polarizations, electron-phonon couplings, strain tuning and hyperfine coupling of single photon emitters in hexagonal boron nitride. The primary aims of this research are to discover the chemical nature of the emitting centres and to facilitate deployment in device applications. Critical analyses of the experimental literature and data interpretation, as well as theoretical approaches used to predict properties, are made. In particular, computational and theoretical limitations and challenges are discussed, with a range of suggestions made to overcome these limitations, striving to achieve realistic predictions concerning the nature of emitting centers. A symbiotic relationship is required in which calculations focus on properties that can easily be measured, whilst experiments deliver results in a form facilitating mass-produced calculations.
Publisher: American Physical Society (APS)
Date: 22-09-2022
Publisher: Springer Science and Business Media LLC
Date: 31-08-2012
DOI: 10.1038/S42005-020-00416-Z
Abstract: The chemical and structural nature of defects responsible for quantum emission in hexagonal boron nitride (h-BN) remain unknown. Optically detected magnetic resonance (ODMR) measured from these defects was reported in two recent papers. In one case, the ODMR was tentatively attributed to the negatively charged boron vacancy, $$V_{\\mathrm{B}}^ -$$ V B − . Here we show how the key optical and magnetic properties vary with location within the bulk and along edges of h-BN sheets for this and the negatively charged nitrogen vacancy, $$V_{\\mathrm{N}}^ -$$ V N − . Sign changes of the axial zero-field interaction parameter D are predicted, as well interchange of singlet and triplet ground states. Based on the latest experimental information, we assign the observed ODMR signal to bulk $$V_{\\mathrm{B}}^ -$$ V B − . The other observed ODMR has some features reminiscent of our calculations for $$V_{\\mathrm{N}}^ -$$ V N − edge defects.
Publisher: Elsevier BV
Date: 11-2021
Publisher: American Association for the Advancement of Science (AAAS)
Date: 19-02-2021
Abstract: Irradiation engineering on hexagonal boron nitride reveals insights into the microscopic nature of quantum emitters.
Publisher: IOP Publishing
Date: 17-06-2020
Publisher: Elsevier BV
Date: 05-2023
Publisher: Elsevier BV
Date: 02-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3NR01511D
Abstract: We narrow down the microscopic origin to 3 out of 26 defect transitions by comparing experiments with ab initio methods and the polaron model. We show excellent agreement between theory and experimental photoluminescence excitation spectroscopy.
Publisher: American Physical Society (APS)
Date: 12-10-2020
Publisher: American Physical Society (APS)
Date: 11-03-2201
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7NR08222C
Abstract: Ar plasma etching and annealing are highly robust in generating oxygen related single photon emitters in hBN.
Publisher: Research Square Platform LLC
Date: 23-05-2022
DOI: 10.21203/RS.3.RS-1637869/V1
Abstract: The spin coherence time of 69 triplet defect centers in 45 different 2D host materials is studied by density functional theory (DFT) and the cluster correlation expansion (CCE) method. Several of the triplets are found to exhibit extraordinarily large spin coherence times making them interesting for quantum information processing. The dependence of the spin coherence time on various factors, including the hyperfine coupling strength, the dipole-dipole coupling, and the nuclear g-factors, are systematically investigated. The analysis shows that the spin coherence time is insensitive to the atomistic details of the defect center and rather is dictated by the nuclear spin properties of the host material. Symbolic regression is then used to derive a simple expression for spin coherence time, which is validated on a test set of 55 doublet defects unseen by the regression model. The simple expression permits order-of-magnitude estimates of the spin coherence time without expensive first principles calculations.
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