Cheng Peng
Associate Scientist, SLAC National Accelerator Laboratory
All Publications
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Understanding the superconductivity and charge density wave interaction through quasi-static lattice fluctuations.
Proceedings of the National Academy of Sciences of the United States of America
2024; 121 (50): e2412182121
Abstract
In unconventional superconductors, coupled charge and lattice degrees of freedom can manifest in ordered phases of matter that are intertwined. In the cuprate family, fluctuating short-range charge correlations can coalesce into a longer-range charge density wave (CDW) order which is thought to intertwine with superconductivity, yet the nature of the interaction is still poorly understood. Here, by measuring subtle lattice fluctuations in underdoped YBa2Cu3O6+y on quasi-static timescales (thousands of seconds) through X-ray photon correlation spectroscopy, we report sensitivity to both superconductivity and CDW. The atomic lattice shows remarkably faster relaxational dynamics upon approaching the superconducting transition at Tc ≈ 65 K. By tracking the momentum dependence, we show that the intermediate scattering function almost monotonically scales with the relaxation distance of atoms away from their average positions above Tc and in the presence of the CDW state, while this peculiar trend is reversed for other temperatures. These observations are consistent with an incipient CDW stabilized by local strain. This work provides insights into the crucial role of relaxational atomic fluctuations for understanding the electronic physics cuprates, which are inherently disordered due to carrier doping.
View details for DOI 10.1073/pnas.2412182121
View details for PubMedID 39630858
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3D Heisenberg universality in the van der Waals antiferromagnet NiPS<sub>3</sub>
NPJ QUANTUM MATERIALS
2024; 9 (1)
View details for DOI 10.1038/s41535-024-00696-6
View details for Web of Science ID 001366178200001
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High-pressure characterization of Ag<sub>3</sub>AuTe<sub>2</sub>: Implications for strain-induced band tuning
APPLIED PHYSICS LETTERS
2024; 125 (21)
View details for DOI 10.1063/5.0223472
View details for Web of Science ID 001360500300018
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Particle-Hole Asymmetric Ferromagnetism and Spin Textures in the Triangular Hubbard-Hofstadter Model
PHYSICAL REVIEW X
2024; 14 (4)
View details for DOI 10.1103/PhysRevX.14.041025
View details for Web of Science ID 001345204400001
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Kitaev physics in the two-dimensional magnet NiPSe<sub>3</sub>
PHYSICAL REVIEW RESEARCH
2024; 6 (3)
View details for DOI 10.1103/PhysRevResearch.6.033206
View details for Web of Science ID 001299530700003
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Emergence of antiferromagnetic correlations and Kondolike features in a model for infinite layer nickelates
NPJ QUANTUM MATERIALS
2024; 9 (1)
View details for DOI 10.1038/s41535-024-00659-x
View details for Web of Science ID 001243372200001
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Machine learning-empowered study of metastable γ-CsPbI<sub>3</sub> under pressure and strain
JOURNAL OF MATERIALS CHEMISTRY A
2024
View details for DOI 10.1039/d4ta00174e
View details for Web of Science ID 001199652300001
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Exfoliable Transition Metal Chalcogenide Semiconductor NbSe2I2.
Inorganic chemistry
2024
Abstract
As the field of exfoliated van der Waals electronics grows to include complex heterostructures, the variety of available in-plane symmetries and geometries becomes increasingly valuable. In this work, we present an efficient chemical vapor transport synthesis of NbSe2I2 with the triclinic space group P1̅. This material contains Nb-Nb dimers and an in-plane crystallographic angle γ = 61.3°. We show that NbSe2I2 can be exfoliated down to few-layer and monolayer structures and use Raman spectroscopy to test the preservation of the crystal structure of exfoliated thin films. The crystal structure was verified by single-crystal and powder X-ray diffraction methods. Density functional theory calculations show triclinic NbSe2I2 to be a semiconductor with a band gap of around 1 eV, with similar band structure features for bulk and monolayer crystals. The physical properties of NbSe2I2 have been characterized by transport, thermal, optical, and magnetic measurements, demonstrating triclinic NbSe2I2 to be a diamagnetic semiconductor that does not exhibit any phase transformation below room temperature.
View details for DOI 10.1021/acs.inorgchem.3c03493
View details for PubMedID 38174989
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Charge order and superconductivity in a two-band model for infinite-layer nickelates
PHYSICAL REVIEW B
2023; 108 (24)
View details for DOI 10.1103/PhysRevB.108.245115
View details for Web of Science ID 001144917900008
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Bayesian experimental design and parameter estimation for ultrafast spin dynamics
MACHINE LEARNING-SCIENCE AND TECHNOLOGY
2023; 4 (4)
View details for DOI 10.1088/2632-2153/ad113a
View details for Web of Science ID 001126295700001
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Capturing dynamical correlations using implicit neural representations.
Nature communications
2023; 14 (1): 5852
Abstract
Understanding the nature and origin of collective excitations in materials is of fundamental importance for unraveling the underlying physics of a many-body system. Excitation spectra are usually obtained by measuring the dynamical structure factor, S(Q, ω), using inelastic neutron or x-ray scattering techniques and are analyzed by comparing the experimental results against calculated predictions. We introduce a data-driven analysis tool which leverages 'neural implicit representations' that are specifically tailored for handling spectrographic measurements and are able to efficiently obtain unknown parameters from experimental data via automatic differentiation. In this work, we employ linear spin wave theory simulations to train a machine learning platform, enabling precise exchange parameter extraction from inelastic neutron scattering data on the square-lattice spin-1 antiferromagnet La2NiO4, showcasing a viable pathway towards automatic refinement of advanced models for ordered magnetic systems.
View details for DOI 10.1038/s41467-023-41378-4
View details for PubMedID 37730824
View details for PubMedCentralID 8662964
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From Stoner to local moment magnetism in atomically thin Cr2Te3.
Nature communications
2023; 14 (1): 5340
Abstract
The field of two-dimensional (2D) ferromagnetism has been proliferating over the past few years, with ongoing interests in basic science and potential applications in spintronic technology. However, a high-resolution spectroscopic study of the 2D ferromagnet is still lacking due to the small size and air sensitivity of the exfoliated nanoflakes. Here, we report a thickness-dependent ferromagnetism in epitaxially grown Cr2Te3 thin films and investigate the evolution of the underlying electronic structure by synergistic angle-resolved photoemission spectroscopy, scanning tunneling microscopy, x-ray absorption spectroscopy, and first-principle calculations. A conspicuous ferromagnetic transition from Stoner to Heisenberg-type is directly observed in the atomically thin limit, indicating that dimensionality is a powerful tuning knob to manipulate the novel properties of 2D magnetism. Monolayer Cr2Te3 retains robust ferromagnetism, but with a suppressed Curie temperature, due to the drastic drop in the density of states near the Fermi level. Our results establish atomically thin Cr2Te3 as an excellent platform to explore the dual nature of localized and itinerant ferromagnetism in 2D magnets.
View details for DOI 10.1038/s41467-023-40997-1
View details for PubMedID 37660171
View details for PubMedCentralID PMC10475109
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Traces of electron-phonon coupling in one-dimensional cuprates.
Nature communications
2023; 14 (1): 3129
Abstract
The appearance of certain spectral features in one-dimensional (1D) cuprate materials has been attributed to a strong, extended attractive coupling between electrons. Here, using time-dependent density matrix renormalization group methods on a Hubbard-extended Holstein model, we show that extended electron-phonon (e-ph) coupling presents an obvious choice to produce such an attractive interaction that reproduces the observed spectral features and doping dependence seen in angle-resolved photoemission experiments: diminished 3kF spectral weight, prominent spectral intensity of a holon-folding branch, and the correct holon band width. While extended e-ph coupling does not qualitatively alter the ground state of the 1D system compared to the Hubbard model, it quantitatively enhances the long-range superconducting correlations and suppresses spin correlations. Such an extended e-ph interaction may be an important missing ingredient in describing the physics of the structurally similar two-dimensional high-temperature superconducting layered cuprates, which may tip the balance between intertwined orders in favor of uniform d-wave superconductivity.
View details for DOI 10.1038/s41467-023-38408-6
View details for PubMedID 37253739
View details for PubMedCentralID PMC10229634
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Enhanced superconductivity by near-neighbor attraction in the doped extended Hubbard model
PHYSICAL REVIEW B
2023; 107 (20)
View details for DOI 10.1103/PhysRevB.107.L201102
View details for Web of Science ID 000986820400004
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A Quantum-Inspired Tensor Network Algorithm for Constrained Combinatorial Optimization Problems
FRONTIERS IN PHYSICS
2022; 10
View details for DOI 10.3389/fphy.2022.906590
View details for Web of Science ID 000837978100001
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Testing the data framework for an AI algorithm in preparation for high data rate X-ray facilities
IEEE. 2022: 1-9
View details for DOI 10.1109/XLOOP56614.2022.00006
View details for Web of Science ID 000968746500001
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Gapless spin liquid and pair density wave of the Hubbard model on three-leg triangular cylinders
NEW JOURNAL OF PHYSICS
2021; 23 (12)
View details for DOI 10.1088/1367-2630/ac3a83
View details for Web of Science ID 000725233200001
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Precursor of pair-density wave in doping Kitaev spin liquid on the honeycomb lattice
NPJ QUANTUM MATERIALS
2021; 6 (1)
View details for DOI 10.1038/s41535-021-00363-0
View details for Web of Science ID 000669205300001
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Doping Quantum Spin Liquids on the Kagome Lattice
ADVANCED QUANTUM TECHNOLOGIES
2021
View details for DOI 10.1002/qute.202000126
View details for Web of Science ID 000612458300001