A5038704910- 2D Materials and Applications
- Perovskite Materials and Applications
- Graphene research and applications
- Quantum and electron transport phenomena
- Advanced Condensed Matter Physics
- Carbon Nanotubes in Composites
- Machine Learning in Materials Science
- Topological Materials and Phenomena
- Inorganic Chemistry and Materials
- Mechanical and Optical Resonators
- Organic and Molecular Conductors Research
- Electronic and Structural Properties of Oxides
- Advanced Memory and Neural Computing
- MXene and MAX Phase Materials
- Diamond and Carbon-based Materials Research
- Molecular Junctions and Nanostructures
- Force Microscopy Techniques and Applications
- Chalcogenide Semiconductor Thin Films
- Magnetic and transport properties of perovskites and related materials
- Semiconductor Quantum Structures and Devices
- Physics of Superconductivity and Magnetism
- Transition Metal Oxide Nanomaterials
- Gas Sensing Nanomaterials and Sensors
- Quantum Dots Synthesis And Properties
- Surface and Thin Film Phenomena
University of Waterloo
2016-2024
Institute of Solid State Physics
2019
Chinese Academy of Sciences
2019
Collaborative Innovation Center of Advanced Microstructures
2019
Nanjing University
2019
University of Science and Technology of China
2019
High Magnetic Field Laboratory
2019
Columbia University
2015-2018
Cornell University
2007-2014
Harvard University
2007
Graphene produced by chemical vapor deposition (CVD) is polycrystalline, and scattering of charge carriers at grain boundaries (GBs) could degrade its performance relative to exfoliated, single-crystal graphene. However, the electrical properties GBs have so far been addressed indirectly without simultaneous knowledge their locations structures. We present measurements on individual in CVD graphene first imaged transmission electron microscopy. Unexpectedly, conductance improves one order...
Spontaneous symmetry-breaking, where the ground state of a system has lower symmetry than underlying Hamiltonian, is ubiquitous in physics. It leads to multiply-degenerate states, each with different "broken" labeled by an order parameter. The variation this parameter space soliton-like features at boundaries broken-symmetry regions and also topological point defects. Bilayer graphene fascinating realization physics, given its interlayer stacking coordinate. been subject intense study...
We conduct a comprehensive study of three different magnetic semiconductors, CrI
We report the observation of a very large negative magnetoresistance effect in van der Waals tunnel junction incorporating thin magnetic semiconductor, CrI3, as active layer. At constant voltage bias, current increases by nearly one million percent upon application 2 T field. The arises from change between antiparallel to parallel alignment spins across different CrI3 layers. Our results elucidate nature state ultrathin and present new opportunities for spintronics based on two-dimensional materials.
Significance The ability to electrically control collective electron states is a central goal of materials research and may allow for the development novel devices. 1T-TaS 2 an ideal candidate such devices due existence various charge ordered in its phase diagram. Although techniques have been demonstrated manipulate order , fundamental understanding effects still lacking, methods used are incompatible with device fabrication. By using both high-resolution transmission microscopy electronic...
Quantum technology has made tremendous strides over the past two decades with remarkable advances in materials engineering, circuit design, and dynamic operation. In particular, integration of different quantum modules benefited from hybrid systems, which provide an important pathway for harnessing natural advantages complementary systems engineering new functionalities. This review article focuses on current frontiers respect to utilizing magnons novel Magnons are fundamental excitations...
Systems simultaneously exhibiting superconductivity and spin-orbit coupling are predicted to provide a route toward topological unconventional electron pairing, driving significant contemporary interest in these materials. Monolayer transition-metal dichalcogenide (TMD) superconductors particular lack inversion symmetry, yielding an antisymmetric form of that admits both spin-singlet spin-triplet components the superconducting wavefunction. Here, we present experimental theoretical study two...
Metal catalyst-free growth of large scale single layer graphene film on a sapphire substrate by chemical vapor deposition (CVD) process at 950 °C is demonstrated. A top-gated field effect transistor (FET) device successfully fabricated without any transfer process. The detailed investigated the atomic force microscopy (AFM) studies.
Two-dimensional (2D) magnetism has been long sought-after and only very recently realized in atomic crystals of magnetic van der Waals materials. So far, a comprehensive understanding the excitations such 2D magnets remains missing. Here we report polarized micro-Raman spectroscopy studies on honeycomb ferromagnet CrI3. We show definitive evidence two sets zero-momentum spin waves at frequencies 2.28 terahertz (THz) 3.75 THz, respectively, that are three orders magnitude higher than those...
Significance Low-dimensional materials, such as 1T-TaS 2 , permit unique phases that arise through electronic and structural reshaping known, respectively, charge-density waves periodic lattice distortions (PLDs). Determining the atomic structure of PLDs is critical toward understanding origin these charge-ordered their effect on properties. Here we reveal microscopic nature at cryogenic room temperature in thin flakes using resolution scanning transmission electron microscopy. Real-space...
While the anomalous Hall effect can manifest even without an external magnetic field, time reversal symmetry is nonetheless still broken by internal magnetization of sample. Recently, it has been shown that certain materials inversion center allow for a nonlinear type whilst retaining symmetry. The may arise from either Berry curvature or through various asymmetric scattering mechanisms. Here, we report observation extremely large $c$-axis in non-centrosymmetric T$_d$ phase MoTe$_2$ and...
Exploring new parameter regimes to realize and control novel phases of matter has been a main theme in modern condensed physics research. The recent discovery 2D magnetism nearly freestanding monolayer atomic crystals already led observations number magnetic phenomena absent bulk counterparts. Such intricate interplays between crystalline structures provide ample opportunities for exploring quantum phase transitions this regime. Here, using field temperature dependent circularly polarized...
Materials that demonstrate large magnetoresistance have attracted significant interest for many decades. Extremely tunnel (TMR) has been reported by several groups across ultrathin CrI3 exploiting the weak antiferromagnetic coupling between adjacent layers. Here, we report a comparative study of TMR in all three chromium trihalides (CrX3, X = Cl, Br, or I) two-dimensional limit. As materials exhibit different transition temperatures and interlayer magnetic ordering ground state, tunneling...
We use scanning photocurrent microscopy (SPCM) to investigate the properties of internal p−n junctions in ambipolar carbon nanotube (CNT) transistors. Our SPCM images show strong signals near metal contacts whose polarity and positions change depending on gate bias. analyzed conjunction with overall conductance also indicate existence gate-dependent evolution n-type operation regime. To determine junction position depletion width a nanometer scale resolution, Gaussian fit was used. measure...
Graphene, a truly two-dimensional hexagonal lattice of carbon atoms, possesses remarkable properties not seen in any other material, including ultrahigh electron mobility, high tensile strength, and uniform broadband optical absorption. While scientists initially studied its intrinsic with small, mechanically exfoliated graphene crystals found randomly, applying this knowledge would require growing large-area films structural physical properties. The science has recently experienced...
We use a combination of Raman spectroscopy and transport measurements to study thin flakes the type-II Weyl semimetal candidate $\mathrm{MoT}{\mathrm{e}}_{2}$ protected from oxidation. In contrast bulk crystals, which undergo phase transition monoclinic inversion symmetry breaking, orthorhombic below $\ensuremath{\sim}250\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, we find that in moderately samples $\ensuremath{\sim}12\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$, single exists up beyond room...
We employ low-frequency Raman spectroscopy to study the nearly commensurate (NC) (C) charge density wave (CDW) transition in $1T\text{\ensuremath{-}}\mathrm{Ta}{\mathrm{S}}_{2}$ ultrathin flakes protected from oxidation. identify additional modes originating C-phase CDW phonons that are distinct those seen bulk $1T\text{\ensuremath{-}}\mathrm{Ta}{\mathrm{S}}_{2}$. attribute these surface layers. By monitoring individual with temperature, we find surfaces undergo a separate, low-hysteresis...
A single photodetector with tunable detection wavelengths and polarization sensitivity can potentially be harnessed for diverse optical applications ranging from imaging sensing to telecommunications. Such a device will require the combination of multiple material systems different structures, band gaps, photoelectrical responses, which is extremely difficult engineer using traditional epitaxial films. Here, we develop multifunctional high-performance photosensor all van der Waals materials....
Memristive devices whose resistance can be hysteretically switched by electric field or current are intensely pursued both for fundamental interest as well potential applications in neuromorphic computing and phase-change memory. When the underlying material exhibits additional charge spin order, resistive states directly coupled, further allowing electrical control of collective phases. The observation abrupt, memristive switching tunneling nanoscale junctions ultrathin CrI3 , a natural...
Transport studies of atomically thin 1T-TaS2 have demonstrated the presence intermediate resistance states across nearly commensurate (NC) to (C) charge density wave (CDW) transition, which can be further switched electrically. While this presents exciting opportunities for material in memristor applications, switching mechanism has remained elusive and could potentially attributed formation inhomogeneous C NC domains flake. Here, we present simultaneous electrical driving scanning...