@article{ISI:001449775100029,
title = {Ultrafast thermo-optical control of spins in a 2D van der Waals semiconductor},
author = {Maciej Dabrowski and Sumit Haldar and Safe Khan and Paul S Keatley and Dimitros Sagkovits and Zekun Xue and Charlie Freeman and Ivan Verzhbitskiy and Theodor Griepe and Unai Atxitia and Goki Eda and Hidekazu Kurebayashi and Elton J G Santos and Robert J Hicken},
doi = {10.1038/s41467-025-58065-1},
times_cited = {0},
year = {2025},
date = {2025-03-21},
journal = {NATURE COMMUNICATIONS},
volume = {16},
number = {1},
publisher = {NATURE PORTFOLIO},
address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY},
abstract = {Laser pulses provide one of the fastest means of manipulating electron spins in magnetic compounds and pave the way to ultrafast operation within magnetic recording, quantum computation and spintronics. However, effective management of the heat deposited during optical excitation is an open challenge. Layered two-dimensional (2D) van der Waals (vdW) materials possess unique thermal properties due to the highly anisotropic nature of their chemical bonding. Here we show how to control the rate of heat flow, and hence the magnetization dynamics, induced by an ultrafast laser pulse within the 2D ferromagnet Cr2Ge2Te6. Using time-resolved beam-scanning magneto-optical Kerr effect microscopy and microscopic spin modelling calculations, we show that by reducing the thickness of the magnetic layers, an enhancement of the heat dissipation rate into the adjacent substrate leads to a substantial reduction in the timescale for magnetization recovery from several nanoseconds down to a few hundred picoseconds. Finally, we demonstrate how the low thermal conductivity across vdW layers may be used to obtain magnetic domain memory behaviour, even after exposure to intense laser pulses. Our findings reveal the distinctive role of vdW magnets in the ultrafast control of heat conduction, spin dynamics and non-volatile memory.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{ISI:001445756900001,
title = {Low-Temperature Contacts and the Coulomb Blockade Effect in Layered Nanoribbons with In-Plane Anisotropy},
author = {Ivan A Verzhbitskiy and Abhishek Mishra and Sanchali Mitra and Zhepeng Zhang and Sarthak Das and Chit Siong Lau and Rainer Lee and Ding Huang and Goki Eda and Yee Sin Ang and Kuan Eng Johnson Goh},
doi = {10.1021/acsnano.4c15086},
times_cited = {0},
issn = {1936-0851},
year = {2025},
date = {2025-03-13},
journal = {ACS NANO},
volume = {19},
number = {11},
pages = {10878-10888},
publisher = {AMER CHEMICAL SOC},
address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
abstract = {One-dimensional (1D) nanoribbons (NRs) constitute rapidly advancing nanotechnology with significant potential for emerging applications such as quantum sensing and metrology. TiS3 nanoribbons exhibit strong in-plane crystal anisotropy, enabling robust 1D confinement and resilience to edge disorder. Nevertheless, charge transport in 1D TiS3 remains relatively unexplored, particularly at low temperatures, where high contact resistance impacts device performance and fundamentally limits its applications. Here, we engineer electrical contacts between a bulk metal and a 1D NR and explore the low-temperature characteristics of the 1D field-effect devices. We report ohmic contacts for 1D TiS3 with temperature-independent contact resistances as low as 2.7 +/- 0.3 k Omegamu m, enabling the study of charge transport at low temperatures (down to 35 mK) and clear observation of the Coulomb blockade effect. We demonstrate single-electron transport in 1D TiS3 and perform excited state spectroscopy and magnetospectroscopy, extracting an out-of-plane electron g-factor, g = 1.8 +/- 0.3.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@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:001448500900003,
title = {Nonmonotonic temperature dependence of electron viscosity and crossover to high-temperature universal viscous fluid in monolayer and bilayer graphene},
author = {Indra Yudhistira and Ramal Afrose and Shaffique Adam},
doi = {10.1103/PhysRevB.111.085433},
times_cited = {0},
issn = {2469-9950},
year = {2025},
date = {2025-02-28},
journal = {PHYSICAL REVIEW B},
volume = {111},
number = {8},
publisher = {AMER PHYSICAL SOC},
address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA},
abstract = {Electrons in quantum matter behave like a fluid when the quantum-mechanical carrier-carrier scattering dominates over other relaxation mechanisms. By combining a microscopic treatment of electron-electron interactions within the random phase approximation with a phenomenological Navier-Stokes-like equation, we predict that in the limit of high temperature and strong Coulomb interactions, both monolayer graphene and bilayer graphene exhibit a universal behavior in dynamic viscosity. We find that the dynamic viscosity to entropy density ratio for bilayer graphene is closer to the holographic bound, suggesting that such a bound might be observable in a condensed matter system. We discuss how this could be observed experimentally using magnetoconductance measurements in a Corbino geometry for a realistic range of temperature and carrier density.},
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},
volume = {19},
number = {6},
pages = {6195-6208},
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}
}