Volume 41 Issue 3

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Highlighted Articles

Xiao-Yun Wang, Chen Dong, and Xiang Liu
Chin. Phys. Lett., 2024, 41 (3): 031201   PDF ( 119 )   HTML ( 28 )
Jing Wu, Shanshan Cao, and Feng Li
Chin. Phys. Lett., 2024, 41 (3): 031202   PDF ( 32 )   HTML ( 11 )
Jianzhi Chen, Aoqian Shi, Yuchen Peng, Peng Peng, and Jianjun Liu
Chin. Phys. Lett., 2024, 41 (3): 037103   PDF ( 50 )   HTML ( 31 )
Zhi-Wen Chang, Wei-Chang Hao, Miguel Bustamante, and Xin Liu
Chin. Phys. Lett., 2024, 41 (3): 037302   PDF ( 98 )   HTML ( 37 )
Zhe Sun and Donglai Feng
Chin. Phys. Lett., 2024, 41 (3): 037303   PDF ( 65 )   HTML ( 17 )
Xingqian Chen, Haozhen Li, Wei Chen, Zengxia Mei, Alexander Azarov, Andrej Kuznetsov, and Xiaolong Du
Chin. Phys. Lett., 2024, 41 (3): 037305   PDF ( 113 )   HTML ( 33 )
Jiawei Hu, Shiyu Zhu, Qianying Hu, Yunhao Wang, Chengmin Shen, Haitao Yang, Xiaoshan Zhu, Qing Huan, Yang Xu, and Hong-Jun Gao
Chin. Phys. Lett., 2024, 41 (3): 037401   PDF ( 295 )   HTML ( 92 )
Yichun Gao, Wenyu Song, Shuai Yang, Zehao Yu, Ruidong Li, Wentao Miao, Yuhao Wang, Fangting Chen, Zuhan Geng, Lining Yang, Zezhou Xia, Xiao Feng, Yunyi Zang, Lin Li, Runan Shang, Qi-Kun Xue, Ke He, and Hao Zhang
Chin. Phys. Lett., 2024, 41 (3): 038502   PDF ( 119 )   HTML ( 34 )

Current Issue

GENERAL
Data-Driven Ai- and Bi-Soliton of the Cylindrical Korteweg–de Vries Equation via Prior-Information Physics-Informed Neural Networks
Shifang Tian, Biao Li, and Zhao Zhang
Chin. Phys. Lett. 2024, 41 (3): 030201 .   DOI: 10.1088/0256-307X/41/3/030201
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By the modifying loss function MSE and training area of physics-informed neural networks (PINNs), we propose a neural networks model, namely prior-information PINNs (PIPINNs). We demonstrate the advantages of PIPINNs by simulating Ai- and Bi-soliton solutions of the cylindrical Korteweg–de Vries (cKdV) equation. Numerical experiments show that our proposed model is able not only to simulate these solitons using the cKdV equation, but also to significantly improve its simulation capability. Compared with the original PINNs, the prediction accuracy of our proposed model is improved by one to three orders of magnitude. Moreover, the accuracy of the PIPINNs is further improved by adding the restriction of conservation of energy.
Solving Quantum Many-Particle Models with Graph Attention Network
Qi-Hang Yu and Zi-Jing Lin
Chin. Phys. Lett. 2024, 41 (3): 030202 .   DOI: 10.1088/0256-307X/41/3/030202
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Deep learning methods have been shown to be effective in representing ground-state wavefunctions of quantum many-body systems, however the existing approaches cannot be easily used for non-square like or large systems. Here, we propose a variational ansatz based on the graph attention network (GAT) which learns distributed latent representations and can be used on non-square lattices. The GAT-based ansatz has a computational complexity that grows linearly with the system size and can be extended to large systems naturally. Numerical results show that our method achieves the state-of-the-art results on spin-1/2 $J_1$–$J_2$ Heisenberg models over the square, honeycomb, triangular, and kagome lattices with different interaction strengths and lattice sizes (up to $24\times 24$ for square lattice). The method also provides excellent results for the ground states of transverse field Ising models on square lattices. The GAT-based techniques are efficient and versatile and hold promise for studying large quantum many-body systems with exponentially sized objects.
THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
Analysis of Strong Coupling Constant with Machine Learning and Its Application
Xiao-Yun Wang, Chen Dong, and Xiang Liu
Chin. Phys. Lett. 2024, 41 (3): 031201 .   DOI: 10.1088/0256-307X/41/3/031201
Abstract   PDF(pc) (1154KB) ( 119 ) PDF(mobile)(1174KB) ( 3 ) HTML ( 28
We investigate the nature of the strong coupling constant and related physics. Through the analysis of accumulated experimental data around the world, we employ the ability of machine learning to unravel its physical laws. The result of our efforts is a formula that captures the expansive panorama of the distribution of the strong coupling constant across the entire energy range. Importantly, this newly derived expression is very similar to the formula derived from the Dyson–Schwinger equations based on the framework of Yang–Mills theory. By introducing the Euler number $e$ into the functional formula of the strong coupling constant at high energies, we successfully solve the puzzle of the infrared divergence, which allows for a seamless transition of the strong coupling constant from the perturbative to the non-perturbative energy regime. Moreover, the obtained ghost and gluon dressing function distribution results confirm that the obtained strong coupling constant formula can well describe the physical properties of the non-perturbed regime. In addition, we study the quantum-chromodynamics strong coupling constant result of the Bjorken sum rule $\varGamma_1^{p-n}$ and the quark–quark static energy $E_0(r)$, and find that the global energy scale can effectively interpret the experimental data. The present results shed light on the puzzling properties of quantum chromodynamics and the intricate interplay of strong coupling constants at both low and high energy scales.
Critical Opalescence and Its Impact on the Jet Quenching Parameter $\hat{q}$
Jing Wu, Shanshan Cao, and Feng Li
Chin. Phys. Lett. 2024, 41 (3): 031202 .   DOI: 10.1088/0256-307X/41/3/031202
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Jet quenching parameter $\hat{q}$ is essential for characterizing the interaction strength between jet partons and nuclear matter. Based on the quark-meson model, we develop a new framework for calculating $\hat{q}$ at finite chemical potentials, in which $\hat{q}$ is related to the spectral function of the chiral order parameter. A mean field perturbative calculation up to the one-loop order indicates that the momentum broadening of jets is enhanced at both high temperature and high chemical potential, and approximately proportional to the parton number density in the partonic phase. We further investigate the behavior of $\hat{q}$ in the vicinity of the critical endpoint (CEP) by coupling our calculation with a recently developed equation of state that includes a CEP in the universality class of the Ising model, from which we discover the partonic critical opalescence, i.e., the divergence of scattering rate of jets and their momentum broadening at the CEP, contributed by scatterings via the $\sigma$ exchange process. Hence, for the first time, jet quenching is connected with the search of CEP.
Production of the $X(4014)$ as the Spin-2 Partner of $X(3872)$ in $e^+e^-$ Collisions
Pan-Pan Shi, Vadim Baru, Feng-Kun Guo, Christoph Hanhart, and Alexey Nefediev
Chin. Phys. Lett. 2024, 41 (3): 031301 .   DOI: 10.1088/0256-307X/41/3/031301
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In 2021, the Belle collaboration reported the first observation of a new structure in the $\psi(2S) \gamma$ final state produced in the two-photon fusion process. In the hadronic molecule picture, this new structure can be associated with the shallow isoscalar $D^*\bar{D}^*$ bound state and as such is an excellent candidate for the spin-2 partner of the $X(3872)$ with the quantum numbers $J^{\rm PC}=2^{++}$ conventionally named $X_2$. In this work we evaluate the electronic width of this new state and argue that its nature is sensitive to its total width, the experimental measurement currently available being unable to distinguish between different options. Our estimates demonstrate that the planned Super $\tau$-Charm Facility offers a promising opportunity to search for and study this new state in the invariant mass distributions for the final states $J/\psi\gamma$ and $\psi(2S)\gamma$.
ATOMIC AND MOLECULAR PHYSICS
Tuning Excitation Transport in a Dissipative Rydberg Ring
Yiwen Han and Wei Yi
Chin. Phys. Lett. 2024, 41 (3): 033201 .   DOI: 10.1088/0256-307X/41/3/033201
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We demonstrate the flexible tunability of excitation transport in Rydberg atoms, under the interplay of controlled dissipation and interaction-induced synthetic flux. Considering a minimum four-site setup, i.e., a triangular configuration with an additional output site, we study the transport of a single excitation, injected into a vertex of the triangle, through the structure. While the long-range dipole-dipole interactions between the Rydberg atoms lead to geometry-dependent Peierls phases in the hopping amplitudes of excitations, we further introduce on-site dissipation to a vertex of the triangle. As a result, both the chirality and destination of the transport can be manipulated through the flux and dissipation. In particular, we illustrate a parameter regime where our Rydberg-ring structure may serve as a switch for transporting the injected excitation through to the output site. The underlying mechanism is then analyzed by studying the chiral trajectory of the excitation and the time-dependent dissipation. The switchable excitation transport reported here offers a flexible tool for quantum control in Rydberg atoms, and holds interesting potentials for applications in quantum simulation and quantum information.
FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS)
An LED-Side-Pumped Intracavity Frequency-Doubled Nd,Ce:YAG Laser Producing a 2 W Q-Switched Red Beam
Jianping Shen, Shaocong Xu, Peng LU, Rongrong Jiang, Wei Wang, Siwei Zhang, Fengyang Xing, Yang Chen, and Liang Chen
Chin. Phys. Lett. 2024, 41 (3): 034201 .   DOI: 10.1088/0256-307X/41/3/034201
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We report a high-average-power acousto-optic (AO) Q-switched intracavity frequency-doubled red laser based on a high-efficiency light-emitting-diode (LED) pumped two-rod Nd,Ce:YAG laser module. Under quasi-continuous wave operation conditions, a maximum output power of 1319.08 nm wavelength was achieved at 11.26 W at a repetition rate of 100 Hz, corresponding to a maximum optical efficiency of 13.9% and a slope efficiency of 17.9%. In the active Q-switched regime, the pulse energy of the laser was as high as 800 µJ at a repetition rate of 10 kHz with a pulse width of 1.5 µs. Under non-critical phase-matched KTP crystal conditions, an average power of 2.03 W of 658.66 nm through intracavity frequency-doubling was obtained at a repetition frequency of 10 kHz with a duration of 1.3 µs, and the $M^{2}$ factor was measured to be about 5.8. To the best of our knowledge, this is the highest average power of an LED-pumped AO Q-switched 1319 nm laser and intracavity frequency-doubled red laser reported to date.
Experimental Investigation of the Anisotropic Thermal Conductivity of C/SiC Composite Thin Slab
Ke-Fan Wu, Hu Zhang, and Gui-Hua Tang
Chin. Phys. Lett. 2024, 41 (3): 034401 .   DOI: 10.1088/0256-307X/41/3/034401
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Fiber-reinforced composites possess anisotropic mechanical and heat transfer properties due to their anisotropic fibers and structure distribution. In C/SiC composites, the out-of-plane thermal conductivity has mainly been studied, whereas the in-plane thermal conductivity has received less attention due to their limited thickness. In this study, the slab module of a transient plane source method is adopted to measure the in-plane thermal conductivity of a 2D plain woven C/SiC composite slab, and the test uncertainty is analyzed numerically. The numerical investigation proves that the slab module is reliable for measuring the isotropic and anisotropic slabs with in-plane thermal conductivity greater than 10 W$\cdot$m$^{-1}\cdot $K$^{-1}$. The anisotropic thermal conductivity of the 2D plain woven C/SiC composite slab is obtained within the temperature range of 20–900 ℃ by combining with a laser flash analysis method to measure the out-of-plane thermal conductivity. The results demonstrate that the out-of-plane thermal conductivity of C/SiC composite decreases with temperature, while its in-plane thermal conductivity first increases with temperature and then decreases, and the ratio of in-plane thermal conductivity to out-of-plane thermal conductivity is within 2.2–3.1.
CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES
Interception of Layered LP-N and HLP-N at Ambient Conditions by Confined Template
Dong-Xue Wang, Jing Fu, Yi Li, Zhen Yao, Shuang Liu, and Bing-Bing Liu
Chin. Phys. Lett. 2024, 41 (3): 036101 .   DOI: 10.1088/0256-307X/41/3/036101
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We propose a feasible strategy of intercepting the layered polymeric nitrogen (LP-N) and hexagonal layered polymeric nitrogen (HLP-N) at ambient conditions by using the confinement templates. The stable mechanism of confined LP-N and HLP-N at ambient conditions is revealed, namely the synergistic effect of charge transfer and vdW confinement effect. The influence rule of interlayer spacing on the stability of LP-N is revealed. Most importantly, the nitrogen content and energy density of recoverable LP-N@graphene (70.59%, 8.15 kJ/g), LP-N@h-BN (70.59%, 7.96 kJ/g), HLP-N@graphene (68.97%, 9.31 kJ/g), and HLP-N@h-BN (69.57%, 8.05 kJ/g) refresh the new record for the confinement polynitrogen system.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
Dynamical $t/U$ Expansion of the Doped Hubbard Model
Wenxin Ding and Rong Yu
Chin. Phys. Lett. 2024, 41 (3): 037101 .   DOI: 10.1088/0256-307X/41/3/037101
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We construct a new $U(1)$ slave-spin representation for the single-band Hubbard model in the large-$U$ limit. The mean-field theory in this representation is more amenable to describe both the spin-charge-separation physics of the Mott insulator at half-filling and the strange metal behavior at finite doping. By employing a dynamical Green's function theory for slave spins, we calculate the single-particle spectral function of electrons. The result is comparable to that in dynamical mean field theories. We then formulate a dynamical $t/U$ expansion for the doped Hubbard model that reproduces the mean-field results at the lowest order of expansion. To the next order of expansion, it naturally yields an effective low-energy theory of a $t$–$J$ model for spinons self-consistently coupled to an $XXZ$ model for the slave spins. We show that the superexchange $J$ is renormalized by doping, in agreement with the Gutzwiller approximation. Surprisingly, we find a new ferromagnetic channel of exchange interactions which survives in the infinite $U$ limit, as a manifestation of the Nagaoka ferromagnetism.
Anisotropic Band Evolution of Bulk Black Phosphorus Induced by Uniaxial Tensile Strain
Yafeng Deng, Yilin Zhang, Yafei Zhao, Yongkang Xu, Xingze Dai, Shuanghai Wang, Xianyang Lu, Yao Li, Yongbing Xu, and Liang He
Chin. Phys. Lett. 2024, 41 (3): 037102 .   DOI: 10.1088/0256-307X/41/3/037102
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We investigate the anisotropic band structure and its evolution under tensile strains along different crystallographic directions in bulk black phosphorus (BP) using angle-resolved photoemission spectroscopy and density functional theory. The results show that there are band crossings in the Z–L (armchair) direction, but not in the Z–A (zigzag) direction. The corresponding dispersion-$k$ distributions near the valence band maximum (VBM) exhibit quasi-linear or quadratic relationships, respectively. Along the armchair direction, the tensile strain expands the interlayer spacing and shifts the VBM to deeper levels with a slope of $-16.2$ meV/% strain. Conversely, the tensile strain along the zigzag direction compresses the interlayer spacing and causes the VBM to shift towards shallower levels with a slope of 13.1 meV/% strain. This work demonstrates an effective method for band engineering of bulk BP by uniaxial tensile strain, elucidates the mechanism behind it, and paves the way for strain-regulated optoelectronic devices based on bulk BP.
Hybrid Skin-Topological Effect Induced by Eight-Site Cells and Arbitrary Adjustment of the Localization of Topological Edge States
Jianzhi Chen, Aoqian Shi, Yuchen Peng, Peng Peng, and Jianjun Liu
Chin. Phys. Lett. 2024, 41 (3): 037103 .   DOI: 10.1088/0256-307X/41/3/037103
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Hybrid skin-topological effect (HSTE) in non-Hermitian systems exhibits both the skin effect and topological protection, offering a novel mechanism for localization of topological edge states (TESs) in electrons, circuits, and photons. However, it remains unclear whether the HSTE can be realized in quasicrystals, and the unique structure of quasicrystals with multi-site cells may provide novel localization phenomena for TESs induced by the HSTE. We propose an eight-site cell in two-dimensional quasicrystals and realize the HSTE with eight-site nonreciprocal intracell hoppings. Furthermore, we can arbitrarily adjust the eigenfield distributions of the TESs and discover domain walls associated with effective dissipation and their correlation with localization. We present a new scheme to precisely adjust the energy distribution in non-Hermitian quasicrystals with arbitrary polygonal outer boundaries.
C-Type Antiferromagnetic Structure of Topological Semimetal CaMnSb$_2$
Bo Li, Xu-Tao Zeng, Qianhui Xu, Fan Yang, Junsen Xiang, Hengyang Zhong, Sihao Deng, Lunhua He, Juping Xu, Wen Yin, Xingye Lu, Huiying Liu, Xian-Lei Sheng, and Wentao Jin
Chin. Phys. Lett. 2024, 41 (3): 037104 .   DOI: 10.1088/0256-307X/41/3/037104
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Determination of the magnetic structure and confirmation of the presence or absence of inversion ($\mathcal{P}$) and time reversal ($\mathcal{T}$) symmetry is imperative for correctly understanding the topological magnetic materials. Here high-quality single crystals of the layered manganese pnictide CaMnSb$_2$ are synthesized using the self-flux method. De Haas–van Alphen oscillations indicate a nontrivial Berry phase of $\sim$ $\pi$ and a notably small cyclotron effective mass, supporting the Dirac semimetal nature of CaMnSb$_2$. Neutron diffraction measurements identify a C-type antiferromagnetic structure below $T_{\rm N} = 303(1)$ K with the Mn moments aligned along the $a$ axis, which is well supported by the density functional theory (DFT) calculations. The corresponding magnetic space group is $Pn'm'a'$, preserving a $\mathcal{P}\times\mathcal{T}$ symmetry. Adopting the experimentally determined magnetic structure, band crossings near the $Y$ point in momentum space and linear dispersions of the Sb $5{\rm p}_{y,\,z}$ bands are revealed by the DFT calculations. Furthermore, our study predicts the possible existence of an intrinsic second-order nonlinear Hall effect in CaMnSb$_2$, offering a promising platform to study the impact of topological properties on nonlinear electrical transports in antiferromagnets.
Constructing Hopf Insulator from Geometric Perspective of Hopf Invariant
Zhi-Wen Chang, Wei-Chang Hao, Miguel Bustamante, and Xin Liu
Chin. Phys. Lett. 2024, 41 (3): 037302 .   DOI: 10.1088/0256-307X/41/3/037302
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We propose a method to construct Hopf insulators based on the study of topological defects from the geometric perspective of Hopf invariant $I$. Firstly, we prove two types of topological defects naturally inhering in the inner differential structure of the Hopf mapping. One type is the four-dimensional point defects, which lead to a topological phase transition occurring at the Dirac points. The other type is the three-dimensional merons, whose topological charges give the evaluations of $I$. Then, we show two ways to establish the Hopf insulator models. One approach is to modify the locations of merons, thereby the contributions of charges to $I$ will change. The other is related to the number of defects. It is found that $I$ will decrease if the number reduces, while increase if additional defects are added. The method developed in this study is expected to provide a new perspective for understanding the topological invariants, which opens a new door in exploring and designing novel topological materials in three dimensions.
Opportunities of Advanced Physical Studies at the Hefei Advanced Light Facility
Zhe Sun and Donglai Feng
Chin. Phys. Lett. 2024, 41 (3): 037303 .   DOI: 10.1088/0256-307X/41/3/037303
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Nontrivial Topological Phases in Ternary Borides M$_{2}$XB$_{2}$ (M = W, Mo; X = Co, Ni)
Danwen Yuan, Changming Yue, Yuefang Hu, and Wei Zhang
Chin. Phys. Lett. 2024, 41 (3): 037304 .   DOI: 10.1088/0256-307X/41/3/037304
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The nontrivial band topologies protected by certain symmetries have attracted significant interest in condensed matter physics. The discoveries of nontrivial topological phases in real materials provide a series of archetype materials to further explore the topological physics. Ternary borides M$_{2}$XB$_{2}$ (M = W, Mo; X = Co, Ni) have been widely investigated as the wear-resistant and high-hardness materials. Based on first-principles calculations, we find the nontrivial topological properties in these materials. Taking W$_{2}$NiB$_{2}$ as an example, this material shows the nodal line semimetal state in the absence of spin-orbit coupling. Two types of nodal lines appear near the Fermi level simultaneously. One is protected by the combined space-inversion and time-reversal symmetry, and the other is by the mirror symmetry. Part of these two-type nodal lines form nodal chains. When spin-orbit coupling is included, these nodal lines are fully gapped and the system becomes a strong topological insulator with nontrivial $Z_{2}$ index (1;000). Our calculations demonstrate that a nontrivial spin-momentum locked surface Dirac cone appears on the $(\bar{{1}}10)$ surface. We also find that other isostructural ternary borides Mo$_{2}$NiB$_{2}$, Mo$_{2}$CoB$_{2}$, and W$_{2}$CoB$_{2}$ possess similar topological band structures. Therefore, our work not only enriches the understanding of band topology for ternary borides, but also lays the foundation for the further study of topological phases manipulation and potential spintronic applications in realistic materials.
Interstitial Doping of SnO$_{2}$ Film with Li for Indium-Free Transparent Conductor
Xingqian Chen, Haozhen Li, Wei Chen, Zengxia Mei, Alexander Azarov, Andrej Kuznetsov, and Xiaolong Du
Chin. Phys. Lett. 2024, 41 (3): 037305 .   DOI: 10.1088/0256-307X/41/3/037305
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SnO$_{2}$ films exhibit significant potential as cost-effective and high electron mobility substitutes for In$_{2}$O$_{3}$ films. In this study, Li is incorporated into the interstitial site of the SnO$_{2}$ lattice resulting in an exceptionally low resistivity of $2.028 \times 10^{-3}\,\Omega \cdot$cm along with a high carrier concentration of $1.398 \times 10^{20}$ cm$^{-3}$ and carrier mobility of 22.02 cm$^{2}$/V$\cdot$s. Intriguingly, Li$_{i}$ readily forms in amorphous structures but faces challenges in crystalline formations. Furthermore, it has been experimentally confirmed that Li$_{i}$ acts as a shallow donor in SnO$_{2}$ with an ionization energy $\Delta E_{\rm D1}$ of $-0.4$ eV, indicating spontaneous occurrence of Li$_{i}$ ionization.
Visualizing the Local Twist Angle Variation within and between Domains of Twisted Bilayer Graphene
Jiawei Hu, Shiyu Zhu, Qianying Hu, Yunhao Wang, Chengmin Shen, Haitao Yang, Xiaoshan Zhu, Qing Huan, Yang Xu, and Hong-Jun Gao
Chin. Phys. Lett. 2024, 41 (3): 037401 .   DOI: 10.1088/0256-307X/41/3/037401
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Moiré superlattices in twisted two-dimensional materials have emerged as ideal platforms for engineering quantum phenomena, which are highly sensitive to twist angles, including both the global value and the spatial inhomogeneity. However, only a few methods provide spatial-resolved information for characterizing local twist angle distribution. Here we directly visualize the variations of local twist angles and angle-dependent evolutions of the quantum states in twisted bilayer graphene by scanning microwave impedance microscopy (sMIM). Spatially resolved sMIM measurements reveal a pronounced alteration in the local twist angle, approximately 0.3$^{\circ}$ over several micrometers in some cases. The variation occurs not only when crossing domain boundaries but also occasionally within individual domains. Additionally, the full-filling density of the flat band experiences a change of over $2 \times 10^{11}$ cm$^{-2}$ when crossing domain boundaries, aligning consistently with the twist angle inhomogeneity. Moreover, the correlated Chern insulators undergo variations in accordance with the twist angle, gradually weakening and eventually disappearing as the deviation from the magic angle increases. Our findings signify the crucial role of twist angles in shaping the distribution and existence of quantum states, establishing a foundational cornerstone for advancing the study of twisted two-dimensional materials.
CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
Quantum State-Resolved Nonadiabatic Dynamics of the H + NaF $\to$ Na + HF Reaction
Ye Mao, Hanghang Chen, Zijiang Yang, Bayaer Buren, and Maodu Chen
Chin. Phys. Lett. 2024, 41 (3): 038201 .   DOI: 10.1088/0256-307X/41/3/038201
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The H + NaF reaction is investigated at the quantum state-resolved level using the time-dependent wave-packet method based on a set of accurate diabatic potential energy surfaces. Oscillatory structures in the total reaction probability indicate the presence of the short-lived intermediate complex, attributed to a shallow potential well and exothermicity. Ro-vibrational state-resolved integral cross sections reveal the inverted population distributions of the product. The HF product favors an angular distribution in the forward hemisphere of 30$^{\circ}$–$60^{\circ}$ within the collision energy range from the threshold to 0.50 eV, which is related to the nonlinear approach of the H atom to the NaF molecule. Quantum generalized deflection functions show that the low-$J$ partial waves contribute primarily to the backward scattering, while the high-$J$ partial waves govern the forward scattering. The correlation between the partial wave $J$ and the scattering angle $\vartheta$ proves that the reaction follows a predominant direct reaction mechanism.
MWCNT Doped Reverse-Mode Polymer Network Liquid Crystals with Frequency Response Property
Jiajun Li, Dongchao Ji, Zhibo Zhang, Yanan Yang, Ruicong Zhang, Tianyu Wang, Yumin Zhang, Wenxin Cao, and Jiaqi Zhu
Chin. Phys. Lett. 2024, 41 (3): 038501 .   DOI: 10.1088/0256-307X/41/3/038501
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Polymer-liquid crystals (PLCs) are common materials for smart windows. However, PLC smart windows usually require high driving voltage to maintain transparency. We synthesized a novel PLC smart film by doping multi-wall carbon nanotubes (MWCNTs) into a reverse-mode polymer network liquid crystal (R-PNLC). It is found that doping MWCNTs could effectively reduce the threshold voltage ($V_{\rm th}$) of R-PNLC from 19.0 V to 8.4 V. Due to co-orientation between MWCNT and LC molecules, the doped R-PNLC is able to maintain a high transmittance of visible light ($\sim$ $80$%) without an applied electric field. We find that doping MWCNTs could change the frequency modulation property of R-PNLC. The doped R-PNLC exhibits a wider frequency modulation range up to 40000 Hz, while the frequency modulation of the undoped R-PNLC reached to a saturation at 23000 Hz. We also tested the electromagnetic interference (EMI) shielding efficiency of R-PNLC and find that the EMI shielding efficiency could be improved by doping only 0.01 wt% MWCNTs into the system. The total shielding effectiveness of 0.01 wt% MWCNT doped R-PNLC was up to 14.91 dB in the frequency band of 5.38–8.17 GHz. This study demonstrates that the films are potentially useful for low-energy-consumption smart windows with enhanced electromagnetic shielding capability.
Hard Superconducting Gap in PbTe Nanowires
Yichun Gao, Wenyu Song, Shuai Yang, Zehao Yu, Ruidong Li, Wentao Miao, Yuhao Wang, Fangting Chen, Zuhan Geng, Lining Yang, Zezhou Xia, Xiao Feng, Yunyi Zang, Lin Li, Runan Shang, Qi-Kun Xue, Ke He, and Hao Zhang
Chin. Phys. Lett. 2024, 41 (3): 038502 .   DOI: 10.1088/0256-307X/41/3/038502
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Semiconductor nanowires coupled to a superconductor provide a powerful testbed for quantum device physics such as Majorana zero modes and gate-tunable hybrid qubits. The performance of these quantum devices heavily relies on the quality of the induced superconducting gap. A hard gap, evident as vanishing subgap conductance in tunneling spectroscopy, is both necessary and desired. A hard gap has been achieved and extensively studied before in III–V semiconductor nanowires (InAs and InSb). In this study, we present the observation of a hard superconducting gap in PbTe nanowires coupled to a superconductor Pb. The gap size $\varDelta$ is $\sim$ 1 meV (maximally 1.3 meV in one device). Additionally, subgap Andreev bound states can also be created and controlled through gate tuning. Tuning a device into the open regime can reveal Andreev enhancement of the subgap conductance. These results pave the way for diverse superconducting quantum devices based on PbTe nanowires.
21 articles