Enhanced van der Waals epitaxy of germanium by out-of-plane dipole moment induced from transferred graphene on TiN/AlN multilayers

2021 ◽  
Vol 130 (20) ◽  
pp. 205301
Author(s):  
Xuejing Wang ◽  
Yeonhoo Kim ◽  
Jon K. Baldwin ◽  
Andrew C. Jones ◽  
Jeeyoon Jeong ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Van Der Waals ◽  
Out Of Plane

scholarly journals Intercorrelated ferroelectrics in 2D van der Waals materials

2021 ◽  
Author(s):  
Yan Liang ◽  
Shiying Shen ◽  
Baibiao Huang ◽  
Ying Dai ◽  
Yandong Ma
Keyword(s):  
Van Der Waals ◽  
Out Of Plane ◽  
Fundamental Phenomenon ◽  
Van Der Waals Materials

2D intercorrelated ferroelectrics, exhibiting a coupled in-plane and out-of-plane ferroelectricity, is a fundamental phenomenon in the field of condensed-mater physics. The current research is based on the paradigm of bi-directional...

scholarly journals A van der Waals antiferromagnetic topological insulator with weak interlayer magnetic coupling

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Chaowei Hu ◽  
Kyle N. Gordon ◽  
Pengfei Liu ◽  
Jinyu Liu ◽  
Xiaoqing Zhou ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Surface States ◽  
Magnetic Coupling ◽  
Anomalous Hall Effect ◽  
Saturation Field ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Ideal System ◽  
Out Of Plane ◽  
Weak Interlayer ◽  
Quantum Phenomena

AbstractMagnetic topological insulators (TI) provide an important material platform to explore quantum phenomena such as quantized anomalous Hall effect and Majorana modes, etc. Their successful material realization is thus essential for our fundamental understanding and potential technical revolutions. By realizing a bulk van der Waals material MnBi4Te7 with alternating septuple [MnBi2Te4] and quintuple [Bi2Te3] layers, we show that it is ferromagnetic in plane but antiferromagnetic along the c axis with an out-of-plane saturation field of ~0.22 T at 2 K. Our angle-resolved photoemission spectroscopy measurements and first-principles calculations further demonstrate that MnBi4Te7 is a Z2 antiferromagnetic TI with two types of surface states associated with the [MnBi2Te4] or [Bi2Te3] termination, respectively. Additionally, its superlattice nature may make various heterostructures of [MnBi2Te4] and [Bi2Te3] layers possible by exfoliation. Therefore, the low saturation field and the superlattice nature of MnBi4Te7 make it an ideal system to investigate rich emergent phenomena.

scholarly journals Consecutive Vibrational Redistribution and Predissociation Processes in s-Tetrazine–Argon Van Der Waals Complexes

1983 ◽  
Vol 2 (3-4) ◽  
pp. 125-135 ◽  
Author(s):  
J. J. F. Ramaekers ◽  
L. B. Krijnen ◽  
H. J. Lips ◽  
J. Langelaar ◽  
R. P. H. Rettschnick
Keyword(s):  
Decay Time ◽  
Van Der Waals ◽  
Stagnation Pressure ◽  
Van Der Waals Complexes ◽  
Supersonic Expansion ◽  
Vibrational Predissociation ◽  
Out Of Plane ◽  
Spectrally Resolved ◽  
Plane Mode

s-Tetrazine argon complexes T−Arn (n = 1, 2) are formed in a supersonic expansion of argon seeded with s-tetrazine. The expansion was conducted through a nozzle of 50 or 100 μm with an argon stagnation pressure between 1 and 1.5 bar. From spectrally resolved measurements it is clear that vibrational redistribution processes as well as vibrational predissociation processes take place after SVL excitation within the complex.From rise and decay time experiments it can be concluded, that after excitation of the 6a1 complex level, the above mentioned processes are consecutive and not parallel. It appears that the out of plane mode 16a couples with the Van der Waals stretching mode. The predissociation rate of the 16a2 complex is observed to be 2.3 × 109 s−1.

scholarly journals Temperature and interlayer coupling induced thermal transport across graphene/2D-SiC van der Waals heterostructure

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Md. Sherajul Islam ◽  
Imon Mia ◽  
A. S. M. Jannatul Islam ◽  
Catherine Stampfl ◽  
Jeongwon Park
Keyword(s):  
High Temperatures ◽  
Thermal Transport ◽  
Van Der Waals ◽  
Thermal Conductance ◽  
Interlayer Coupling ◽  
Phonon Modes ◽  
Out Of Plane ◽  
System Temperature ◽  
Non Equilibrium Molecular Dynamics ◽  
Increasing Temperature

AbstractGraphene based two-dimensional (2D) van der Waals (vdW) materials have attracted enormous attention because of their extraordinary physical properties. In this study, we explore the temperature and interlayer coupling induced thermal transport across the graphene/2D-SiC vdW interface using non-equilibrium molecular dynamics and transient pump probe methods. We find that the in-plane thermal conductivity κ deviates slightly from the 1/T law at high temperatures. A tunable κ is found with the variation of the interlayer coupling strength χ. The interlayer thermal resistance R across graphene/2D-SiC interface reaches 2.71 $$\times$$ × 10–7$${\text{Km}}^{2} /{\text{W}}$$ Km 2 / W at room temperature and χ = 1, and it reduces steadily with the elevation of system temperature and χ, demonstrating around 41% and 56% reduction with increasing temperature to 700 K and a χ of 25, respectively. We also elucidate the heat transport mechanism by estimating the in-plane and out-of-plane phonon modes. Higher phonon propagation possibility and Umklapp scattering across the interface at high temperatures and increased χ lead to the significant reduction of R. This work unveils the mechanism of heat transfer and interface thermal conductance engineering across the graphene/2D-SiC vdW heterostructure.

scholarly journals Exceptional in-plane and interfacial thermal transport in graphene/2D-SiC van der Waals heterostructures

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Md. Sherajul Islam ◽  
Imon Mia ◽  
Shihab Ahammed ◽  
Catherine Stampfl ◽  
Jeongwon Park
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Van Der Waals ◽  
New Physics ◽  
Infinite Length ◽  
Interatomic Potentials ◽  
Van Der Waals Heterostructures ◽  
Functional Efficiency ◽  
Out Of Plane ◽  
The Impact

AbstractGraphene based van der Waals heterostructures (vdWHs) have gained substantial interest recently due to their unique electrical and optical characteristics as well as unprecedented opportunities to explore new physics and revolutionary design of nanodevices. However, the heat conduction performance of these vdWHs holds a crucial role in deciding their functional efficiency. In-plane and out-of-plane thermal conduction phenomena in graphene/2D-SiC vdWHs were studied using reverse non-equilibrium molecular dynamics simulations and the transient pump-probe technique, respectively. At room temperature, we determined an in-plane thermal conductivity of ~ 1452 W/m-K for an infinite length graphene/2D-SiC vdWH, which is superior to any graphene based vdWHs reported yet. The out-of-plane thermal resistance of graphene → 2D-SiC and 2D-SiC → graphene was estimated to be 2.71 × 10−7 km2/W and 2.65 × 10−7 km2/W, respectively, implying the absence of the thermal rectification effect in the heterobilayer. The phonon-mediated both in-plane and out-of-plane heat transfer is clarified for this prospective heterobilayer. This study furthermore explored the impact of various interatomic potentials on the thermal conductivity of the heterobilayer. These findings are useful in explaining the heat conduction at the interfaces in graphene/2D-SiC vdWH and may provide a guideline for efficient design and regulation of their thermal characteristics.

scholarly journals Graphene fatigue through van der Waals interactions

2020 ◽  
Vol 6 (42) ◽  
pp. eabb1335
Author(s):  
Teng Cui ◽  
Kevin Yip ◽  
Aly Hassan ◽  
Guorui Wang ◽  
Xingjian Liu ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Flexible Electronics ◽  
Shear Fracture ◽  
Van Der Waals ◽  
Van Der Waals Interactions ◽  
Pristine Graphene ◽  
Plane Shear ◽  
Dynamic Reliability ◽  
Polymer Interface ◽  
Out Of Plane

Graphene is often in contact with other materials through weak van der Waals (vdW) interactions. Of particular interest is the graphene-polymer interface, which is constantly subjected to dynamic loading in applications, including flexible electronics and multifunctional coatings. Through in situ cyclic loading, we directly observed interfacial fatigue propagation at the graphene-polymer interface, which was revealed to satisfy a modified Paris’ law. Furthermore, cyclic loading through vdW contact was able to cause fatigue fracture of even pristine graphene through a combined in-plane shear and out-of-plane tear mechanism. Shear fracture was found to mainly initiate at the fold junctions induced by cyclic loading and propagate parallel to the loading direction. Fracture mechanics analysis was conducted to explain the kinetics of an exotic self-tearing behavior of graphene during cyclic loading. This work offers mechanistic insights into the dynamic reliability of graphene and graphene-polymer interface, which could facilitate the durable design of graphene-based structures.

Probing Effective Out‐of‐Plane Piezoelectricity in van der Waals Layered Materials Induced by Flexoelectricity

Small ◽  
2019 ◽  
Vol 15 (46) ◽  
pp. 1903106 ◽  
Author(s):  
Xiang Wang ◽  
Anyang Cui ◽  
Fangfang Chen ◽  
Liping Xu ◽  
Zhigao Hu ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Layered Materials ◽  
Out Of Plane

Proton and fluorine magnetic resonance studies of some benzoyl fluoride derivatives. Sensitivity of the fluorine shifts to intramolecular van der Waals interactions and steric effects

1977 ◽  
Vol 55 (22) ◽  
pp. 3936-3941 ◽  
Author(s):  
Ted Schaefer ◽  
Kirk Marat ◽  
Kalvin Chum ◽  
Alexander F. Janzen
Keyword(s):  
Magnetic Resonance ◽  
Van Der Waals ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Van Der Waals Interactions ◽  
Proton Proton ◽  
Out Of Plane ◽  
Spin Coupling Constants ◽  
The Individual ◽  
Spin Spin Coupling

The syntheses and the analyses of the high resolution proton and fluorine magnetic resonance spectra of the 3-fluoro-4-methyl-, 2-fluoro-5-chloro-, 2-fluoro-6-chloro-, 2,6-difluoro-, and of the pentafluorobenzoyl fluorides are reported. The spin–spin coupling constants over five bonds between the sidechain fluorine-19 and the ring protons are sensitive to intrinsic substituent perturbations. Their use in the deduction of conformational preferences is much more problematical than is the use of the corresponding proton–proton couplings in benzaldehyde derivatives. The 2-fluoro-6-chloro compound is nonplanar, as indicated by a finite magnitude of the long-range proton–fluorine coupling over six bonds. The nonplanarity is also indicated by a comparison of the through-space fluorine–fluorine coupling to those in the other compounds. The chemical shift of the sidechain fluorine moves to low field by over 35 ppm as the size of the two ortho substituents increases. The individual shifts are discussed in terms of intramolecular van der Waals interactions and of out-of-plane twisting of the COF group.

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