@article{ISI:001403236800001,
title = {Small polarons mediated near-room-temperature metal-insulator transition in vanadium dioxide and their hopping dynamics},
author = {Xiongfang Liu and Tong Yang and Shanquan Chen and Jing Wu and Chi Sin Tang and Yuanjie Ning and Zuhuang Chen and Liang Dai and Mengxia Sun and Mingyao Chen and Kun Han and Difan Zhou and Shengwei Zeng and Shuo Sun and Sensen Li and Ming Yang and Mark B H Breese and Chuanbing Cai and Thirumalai Venkatesan and Andrew T S Wee and Xinmao Yin},
doi = {10.1063/5.0236807},
times_cited = {0},
issn = {1931-9401},
year = {2025},
date = {2025-03-01},
journal = {APPLIED PHYSICS REVIEWS},
volume = {12},
number = {1},
publisher = {AIP Publishing},
address = {1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA},
abstract = {Researchers pursuing advanced photoelectric devices have discovered near room-temperature metal-insulator transitions (MIT) in nonvolatile VO2. Despite theoretical investigations suggesting that polaron dynamics mediate the MIT, direct experimental evidence remains scarce. In this study, we present direct evidence of the polaron state in insulating VO2 through high-resolution spectroscopic ellipsometry measurements and first-principles calculations. We illustrate the complementary role of polaron dynamics in facilitating Peierls and Mott transitions, thereby contributing to the MIT processes. Furthermore, our observations and characterizations of conventional metallic and correlated plasmons in the respective phases of the VO2 film offer valuable insight into their electron structures. This investigation enhances comprehension of the MIT mechanism in correlated systems and underscores the roles of polarons, lattice distortions, and electron correlations in facilitating phase transition processes in strongly correlated systems. Additionally, the detailed detection of small polarons and plasmons serves as inspiration for the development of new device functionalities.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001416560700001,
title = {Electron Ptychography for Atom-by-Atom Quantification of 1D Defect Complexes in Monolayer MoS_{2}},
author = {Leyi Loh and Shoucong Ning and Daria Kieczka and Yuan Chen and Jianmin Yang and Zhe Wang and Stephen J Pennycook and Goki Eda and Alexander L Shluger and Michel Bosman},
doi = {10.1021/acsnano.4c14988},
times_cited = {0},
issn = {1936-0851},
year = {2025},
date = {2025-02-07},
journal = {ACS NANO},
publisher = {AMER CHEMICAL SOC},
address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
abstract = {Defect complexes can induce beneficial functionalities in two-dimensional (2D) semiconductors. However, understanding their formation mechanism with single-atom sensitivity has proven to be challenging for light elements using conventional transmission electron microscopy (TEM) techniques. Here, we demonstrate the atom-resolved formation of various one-dimensional (1D) defect complexes-consisting of rhenium dopants, sulfur interstitials, and sulfur vacancies-in monolayer MoS2 by applying electron ptychography to our four-dimensional scanning transmission electron microscopy (4D-STEM) data sets. Our image resolution of 0.35 angstrom and a spatial precision of 2 pm allow us to achieve accurate matching between experimental structures and density functional theory (DFT) simulations at the atomic level. Additionally, we utilize out-of-focus ptychography to observe defect formation processes at dose rates comparable to those used in conventional TEM imaging, while maintaining a large field of view. This study demonstrates the systematic application of electron ptychography to extensive 4D-STEM data sets for quantitative defect imaging in 2D materials. We provide direct, atomically precise evidence that critical defect densities govern the formation of extended 1D defect complexes. For instance, we show that sulfur single-vacancy lines form when the vacancy density reaches 5 x 1013 cm-2 and transform into double-vacancy lines beyond 8 x 1013 cm-2. Rhenium-dopant lines emerge at a dopant concentration higher than 3 x 1013 cm-2, where metastable sulfur interstitial-vacancy lines also form as the cumulative electron dose reaches 3 x 105 e/angstrom 2, initiating a local nucleation of the 1T ' phase. Our results highlight the potential of electron ptychography for high-precision defect characterization and engineering in ultrathin 2D materials.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001396476700001,
title = {Revealing Multistep Phase Separation in Metal Alloy Nanoparticles with \textit{In Situ} Transmission Electron Microscopy},
author = {Yingying Jiang and Zicong Marvin Wong and Hongwei Yan and Teck Leong Tan and Utkur Mirsaidov},
doi = {10.1021/acsnano.4c16095},
times_cited = {0},
issn = {1936-0851},
year = {2025},
date = {2025-01-14},
journal = {ACS NANO},
volume = {19},
number = {3},
pages = {3886-3894},
publisher = {AMER CHEMICAL SOC},
address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
abstract = {Phase separation plays a crucial role in many natural and industrial processes, such as the formation of clouds and minerals and the distillation of crude oil. In metals and alloys, phase separation is an important approach often utilized to improve their mechanical strength for use in construction, automobile, and aerospace manufacturing. Despite its importance in many processes, the atomic details of phase separation are largely unknown. In particular, it is unclear how a different crystal phase emerges from the parent alloy. Here, using real-time in situ transmission electron microscopy, we describe the stages of the phase separation in face-centered cubic (fcc) AuRu alloy nanoparticles, resulting in a Ru phase with a hexagonal close-packed (hcp) crystal structure. Our observation reveals that the hcp Ru phase forms in two steps: the spinodal decomposition of the alloy produces metastable fcc Ru clusters, and as they grow larger, these clusters transform into hcp Ru domains. Our calculations indicate that the primary reason for the fcc-to-hcp transformation is the size-dependent competition between the interfacial and bulk energies of Ru domains. These insights into elusive, transient steps in the phase separation of alloys can aid in engineering nanomaterials with unconventional phases.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001396241000050,
title = {From 2D kaolinite to 3D amorphous cement},
author = {Juan A G Carrio and Ricardo K Donato and Alexandra Carvalho and Gavin K W Koon and Katarzyna Z Donato and Xin Hui Yau and Dmytro Kosiachevskyi and Karen Lim and Vedarethinam Ravi and Josny Joy and Kelda Goh and Jose Vitorio Emiliano and Jerome E Lombardi and Castro A H Neto},
doi = {10.1038/s41598-024-81882-1},
times_cited = {0},
issn = {2045-2322},
year = {2025},
date = {2025-01-11},
journal = {SCIENTIFIC REPORTS},
volume = {15},
number = {1},
publisher = {NATURE PORTFOLIO},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {Kaolinite is a single 2D layer of kaolin or metakaolin (MK), common clays that can be characterized as layered 3D materials. We show that because of its chemical composition, kaolinite can be converted into an amorphous 3D material by chemical means. This dimensional transformation is possible due to the large surface to volume ratio and chemical reactivity of kaolinite. We investigate the formation and influence of quasi- or nanocrystalline phases in MK-based alkali-activated materials (AAM) that are related to the Si/Al ratio. We analyze the formation of an AAM from a MK precursor, which is a 3D bonded network that preserves the layered structure at the nanometer scale. We also exfoliate the remaining layered phase to examine the effects of the alkali-activation in the final sheet structures embedded within the amorphous network. The final material can be used as a cement with no carbon dioxide produced by the transformation reaction.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001416427700003,
title = {Unified theoretical framework for Kondo superconductors: Periodic Anderson impurities with attractive pairing and Rashba spin-orbit coupling},
author = {Shangjian Jin and Darryl C W Foo and Tingyu Qu and Barbaros Ozyilmaz and Shaffique Adam},
doi = {10.1103/PhysRevB.111.014505},
times_cited = {0},
issn = {2469-9950},
year = {2025},
date = {2025-01-08},
journal = {PHYSICAL REVIEW B},
volume = {111},
number = {1},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Magnetic superconductors manifest a fascinating interplay between their magnetic and superconducting properties. This becomes evident, for example, in the significant enhancement of the upper critical field observed in uranium-based superconductors, or the destruction of superconductivity well below the superconducting transition temperature Tc in cobalt-doped NbSe2. In this work, we argue that the Kondo interaction plays a pivotal role in governing these behaviors. By employing a periodic Anderson model, we study the Kondo effect in superconductors with either singlet or triplet pairing. In the regime of small impurity energies and high doping concentrations, we find the emergence of a Kondo resistive region below Tc. While a magnetic field suppresses singlet superconductivity, it stabilizes triplet pairing through the screening of magnetic impurities, inducing reentrant superconductivity at high fields. Moreover, introducing an antisymmetric spin-orbital coupling suppresses triplet superconductivity. This framework provides a unified picture to understand the observation of Kondo effect in NbSe2 as well as the phase diagrams in Kondo superconductors such as UTe2 and URhGe.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}