2,012 results on '"Su, Gang"'
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52. Irisin Attenuates Apoptosis Following Ischemia–Reperfusion Injury Through Improved Mitochondria Dynamics and ROS Suppression Mediated Through the PI3K/Akt/mTOR Axis
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Liu, Ji-fei, Su, Gang, Chen, Li-xia, Zhou, Juan-ping, Gao, Juan, Zhang, Jia-jia, Wu, Qiong-hui, Chen, Wei, Chen, De-yi, and Zhang, Zhen-chang
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- 2023
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53. Quantum Heaviside Eigen Solver
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Sun, Zheng-Zhi and Su, Gang
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Quantum Physics - Abstract
Solving Hamiltonian matrix is a central task in quantum many-body physics and quantum chemistry. Here we propose a novel quantum algorithm named as a quantum Heaviside eigen solver to calculate both the eigen values and eigen states of the general Hamiltonian for quantum computers. A quantum judge is suggested to determine whether all the eigen values of a given Hamiltonian is larger than a certain threshold, and the lowest eigen value with an error smaller than $\varepsilon $ can be obtained by dichotomy in $O\left( {{{\log }}{1 \over \varepsilon }} \right)$ iterations of shifting Hamiltonian and performing quantum judge. A quantum selector is proposed to calculate the corresponding eigen states. Both quantum judge and quantum selector achieve quadratic speedup from amplitude amplification over classical diagonalization methods. The present algorithm is a universal quantum eigen solver for Hamiltonian in quantum many-body systems and quantum chemistry. We test this algorithm on the quantum simulator for a physical model to show its good feasibility.
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- 2021
54. T-carbon: experiments, properties, derivatives and potential applications
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Yi, Xinwei, Zhang, Zhen, Liao, Zhengwei, Dong, Xuejuan, You, Jingyang, and Su, Gang
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Condensed Matter - Materials Science - Abstract
Carbon is an extremely versatile element and carbon allotropes are very useful in all aspects of life and scientific research. T-carbon is a novel carbon allotrope with many appealing properties. Since the proposal of T-carbon, there has been a lot of intensive studies devoted to its physical, chemical, optical, magnetic, thermoelectrical and topological properties and possible applications in diverse areas in recent years. In this review, we provide a comprehensive review on the advances of the experiments, intriguing properties and various potential applications of T-carbon in energy storage, optoelectronics, thermoelectrics, topological states, etc. As intercalation and doping are effective methods to modify the electronic structure of materials or even to convert into sparkly different new structures or phases, we also discuss different atom doped T-carbon, which exhibit more intriguing properties and lead to promising potential applications in solar cells, photocatalysis, magnetism, superconductivity and so on. In addition, it is interesting to mention that the hydrogenated T-carbon molecules werefound to be possibly related to the physical origin of the UV extinction feature in interstellar medium that has been the half-century long unsolved puzzle. Many novel derivative structures either derived or inspired from T-carbon are included as well. Finally, we give prospects and outlook for future directions of study on T-carbon and related structures.
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- 2021
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55. Emergent magnetic states due to stacking and strain in the van der Waals magnetic trilayer CrI3
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Zhang, Zhen, You, Jing-Yang, Gu, Bo, and Su, Gang
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Condensed Matter - Materials Science - Abstract
Recently, three different magnetic states were observed experimentally in trilayer CrI3 under pressure,including ferromagnetic (FM)-upupup, FM-downupdown and FM-upupdown. To reveal the nature of the observed three magnetic states, we studied the magnetic properties of four possible stacking structures in trilayer CrI3: I (rhombohedral), II (monoclinic), III (hexagonal) and IV (triclinic). We find that all four stacking structures possess the FM-upupup ground state. After applying a few strains, the FM-downupdown becomes the ground state in II and III structures, and the FM-upupdown is preferred in IV structure, while the FM-upupup persists in I structure. Our results unveil that the three magnetic states observed in trilayer CrI3 may correspond to different stacking structures with small tensile strains, which can well interpret the experimentally obtained pressure dependent interlayer coupling and Curie temperature. Our present study paves a way to design the magnetic multilayers with required magnetic states by tuning stacking and strain., Comment: 8 pages, 4 figures
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- 2021
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56. Enhanced superconductivity in C-S-H compounds at high pressure
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Liao, Zheng-Wei, Zhang, Zhen, You, Jing-Yang, Gu, Bo, and Su, Gang
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Condensed Matter - Superconductivity - Abstract
Recently, the superconducting transition temperature Tc = 287 K has been experimentally obtained in the material composed of carbon, sulfur, and hydrogen under the high pressure of 267 GPa. The material structure is unknown yet, where the carbon and sulfur were added at a molar ratio of 1:1. Here, fixing the molar ratio of C : S = 1:1, we studied several possible C-S-H structures, and found a new stable structure C2S2H4 using the first-principles calculations. The C2S2H4 shows an insulator-to-metal transition and the superconducting ground state at the pressure of 64 GPa, and its Tc can reach 16.5 K at 300 GPa. In addition, we found another stable structure of C2S3H4, whose Tc is 47.4 K at 300 GPa. The calculations show that the added S atom in C2S3H4 breaks part of C-H bonds in C2S2H4, makes the vibration of H atom at a lower frequency, and thus enhances the electro-phonon coupling and Tc. Our results suggest that the molar ratio of C:S lower than 1:1 in the C-S-H systems may be favorable to enhance Tc. This can be useful to figure out the structure of the C-S-H material with room temperature Tc in the recent experiment.
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- 2021
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57. Theory of Nonlinear Response for Charge and Spin Currents
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Zhang, Zhi-Fan, Zhu, Zhen-Gang, and Su, Gang
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Condensed Matter - Materials Science - Abstract
The nonlinear Hall effect, which is the second-order harmonic charge Hall effect from the Berry curvature dipole in momentum space, has received much attention recently. As the responses to higher harmonics of the driving ac electric field are prominent and measurable, we develop a general nonlinear theory by taking the charge and spin currents as well as the longitudinal and transverse effects into account. We introduce the expansion order of the electric field and Berry curvature multipole moment, where the Berry curvature dipole is a particular one manifesting itself at the second harmonic order and the second expansion order of the electric field. There are four cases with conserving or breaking the time-reversal symmetry (TRS) and inversion symmetry (IS). We find a specific ``selection rule" that only longitudinal odd harmonic order charge currents exist for conserving both the TRS and IS, and with breaking both symmetries, all harmonic order charge and spin currents are nonzero. With conserving TRS and breaking IS, the charge Hall current exists at even harmonic order, and the longitudinal charge current occurs at odd harmonic order. Only the longitudinal spin current survives at even harmonic order. With breaking TRS and conserving IS, only odd harmonic order charge and spin currents can appear. Moreover, we observe that every harmonic order current contains a series of infinite-order expansion of the electric field. We further show that the Berry curvature dipole and quadrupole can be determined by measuring the second and fourth harmonic order currents in experiments. This may open a way to explore the higher responses of an ac driving system.
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- 2021
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58. Fundamental Distinction between Intrinsic and Extrinsic Nonlinear Thermal Hall Effects
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Zhou, Da-Kun, Zhang, Zhi-Fan, Yu, Xiao-Qin, Zhu, Zhen-Gang, and Su, Gang
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Condensed Matter - Materials Science - Abstract
We theoretically investigated the fundamental distinction between intrinsic and extrinsic nonlinear thermal Hall effect in the presence of disorder at the second-order response to the temperature gradient in terms of the semi-classical Boltzmann equation. We found that, at low temperatures, the intrinsic contribution of the nonlinear thermal Hall conductivity is proportional to the square of temperature, whereas the extrinsic contributions (side-jump and skew-scattering) are independent of temperature. This distinct dependency on temperature provide a new approach to readily distinguish the intrinsic and extrinsic contributions. Specifically, we analysed the nonlinear thermal Hall effect for a tilted two-dimensional massive Dirac material. In particular, we showed that when the Fermi energy is located at the Dirac point, the signal is solely from the intrinsic mechanism; when the Fermi energy is higher, the extrinsic contributions are dominant, which are uncovered to be two to three orders of magnitude larger than the intrinsic contribution.
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- 2021
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59. A new anisotropic solar radiation model based on the principle of photothermal integration
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Yao, Wanxiang, Song, Mengjia, Huang, Yu, Xu, Puyan, Li, Xianli, Su, Gang, and Gao, Weijun
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- 2024
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60. Possible intermediate quantum spin liquid phase in α-RuCl3 under high magnetic fields up to 100 T
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Zhou, Xu-Guang, Li, Han, Matsuda, Yasuhiro H., Matsuo, Akira, Li, Wei, Kurita, Nobuyuki, Su, Gang, Kindo, Koichi, and Tanaka, Hidekazu
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- 2023
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61. Observation of flat band, Dirac nodal lines and topological surface states in Kagome superconductor CsTi3Bi5
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Yang, Jiangang, Yi, Xinwei, Zhao, Zhen, Xie, Yuyang, Miao, Taimin, Luo, Hailan, Chen, Hao, Liang, Bo, Zhu, Wenpei, Ye, Yuhan, You, Jing-Yang, Gu, Bo, Zhang, Shenjin, Zhang, Fengfeng, Yang, Feng, Wang, Zhimin, Peng, Qinjun, Mao, Hanqing, Liu, Guodong, Xu, Zuyan, Chen, Hui, Yang, Haitao, Su, Gang, Gao, Hongjun, Zhao, Lin, and Zhou, X. J.
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- 2023
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62. Evaluating the efficacy and safety of oral triple sequential combination therapy for treating patients with pulmonary arterial hypertension: A multicenter retrospective study
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Qin‐Hua Zhao, Jun Chen, Fa‐Dong Chen, Hong‐Yun Ruan, Wei Zhang, Yan‐Li Zhou, Qi‐Qi Wang, Xiao‐Ling Xu, Ke‐Fu Feng, Jian‐Zhou Guo, Su‐Gang Gong, Rui‐Feng Zhang, and Lan Wang
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event ,oral sequential triple combination therapy ,pulmonary arterial hypertension ,risk stratification ,survival ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 ,Diseases of the respiratory system ,RC705-779 - Abstract
Abstract This study aimed to evaluate the effectiveness and safety of an oral sequential triple combination therapy with selexipag after dual combination therapy with endothelin receptor antagonist (ERA) and phosphodiesterase‐5 inhibitor (PDE5I)/riociguat in pulmonary arterial hypertension (PAH) patients. A total of 192 PAH patients from 10 centers had received oral sequential selexipag therapy after being on dual‐combination therapy with ERA and PDE5i/riociguat for a minimum of 3 months. Clinical data were collected at baseline and after 6 months of treatment. The study analyzed the event‐free survival at 6 months and all‐cause death over 2 years. At baseline, the distribution of patients among the risk groups was as follows: 22 in the low‐risk group, 35 in the intermediate‐low‐risk group, 91 in the intermediate‐high‐risk group, and 44 in the high‐risk group. After 6 months of treatment, the oral sequential triple combination therapy resulted in reduced NT‐proBNP levels (media from 1604 to 678 pg/mL), a decline in the percentage of WHO‐FC III/IV (from 79.2% to 60.4%), an increased in the 6MWD (from 325 ± 147 to 378 ± 143 m) and a rise in the percentage of patients with three low‐risk criteria (from 5.7% to 13.5%). Among the low‐risk group, there was an improvement in the right heart remodeling, marked by a decrease in right atrium area and eccentricity index. The intermediate‐low‐risk group exhibited significant enhancements in WHO‐FC and tricuspid annular plane systolic excursion. For those in the intermediate‐high and high‐risk groups, there were marked improvements in activity tolerance, as reflected by WHO‐FC and 6MWD. The event‐free survival rate at 6 months stood at 88%. Over the long‐term follow‐up, the survival rates at 1 and 2 years were 86.5% and 86.0%, respectively. In conclusion, the oral sequential triple combination therapy enhanced both exercise capacity and cardiac remodeling across PAH patients of different risk stratifications.
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- 2024
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63. Enhanced spin-orbit coupling and orbital moment in ferromagnets by electron correlations
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Liu, Ze, You, Jing-Yang, Gu, Bo, Maekawa, Sadamichi, and Su, Gang
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
In atomic physics, the Hund rule says that the largest spin and orbital state is realized due to the interplay of the spin-orbit coupling (SOC) and the Coulomb interactions. Here, we show that in ferromagnetic solids the effective SOC and the orbital magnetic moment can be dramatically enhanced by a factor of $1/[1-(2U^\prime-U-J_H)\rho_0]$, where $U$ and $U^\prime$ are the on-site Coulomb interaction within the same oribtals and between different orbitals, respectively, $J_H$ is the Hund coupling, and $\rho_0$ is the average density of states. This factor is obtained by using the two-orbital as well as five-orbital Hubbard models with SOC. We also find that the spin polarization is more favorable than the orbital polarization, being consistent with experimental observations. This present work provides a fundamental basis for understanding the enhancements of SOC and orbital moment by Coulomb interactions in ferromagnets, which would have wide applications in spintronics., Comment: 6 pages, 1 figure
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- 2021
64. The atlas of ferroicity in two dimensional MGeX3 family: room-temperature ferromagnetic half metals and unexpected ferroelectricity and ferroelasticity
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Hao, Kuan-Rong, Ma, Xing-Yu, Lyu, Hou-Yi, Zhu, Zhen-Gang, Yan, Qing-Bo, and Su, Gang
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Condensed Matter - Materials Science - Abstract
Two-dimensional (2D) ferromagnetic and ferroelectric materials attract unprecedented attention due to the spontaneous-symmetry-breaking induced novel properties and multifarious potential applications. Here we systematically investigate a large family (148) of 2D MGeX3 (M = metal elements, X = O/S/Se/Te) by means of the high-throughput first-principles calculations, and focus on their possible ferroic properties including ferromagnetism, ferroelectricity, and ferroelasticity. We discover eight stable 2D ferromagnets including five semiconductors and three half-metals, 21 2D antiferromagnets, and 11 stable 2D ferroelectric semiconductors including two multiferroic materials. Particularly, MnGeSe3 and MnGeTe3 are predicted to be room-temperature 2D ferromagnetic half metals with Tc of 490 and 308 K, respectively. It is probably for the first time that ferroelectricity is uncovered in 2D MGeX3 family, which derives from the spontaneous symmetry breaking induced by unexpected displacements of Ge-Ge atomic pairs, and we also reveal that the electric polarizations are in proportion to the ratio of electronegativity of X and M atoms, and IVB group metal elements are highly favored for 2D ferroelectricity. Magnetic tunnel junction and water-splitting photocatalyst based on 2D ferroic MGeX3 are proposed as examples of wide potential applications. The atlas of ferroicity in 2D MGeX3 materials will spur great interest in experimental studies and would lead to diverse applications., Comment: 25 pages, 6 figures
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- 2021
65. Research on Quantum Blockchain Domestic Cryptographic Algorithm Support Library
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Zhang, Chunfeng, Su, Gang, Wang, Guoyi, Huang, Jianzhong, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Tan, Kay Chen, Series Editor, Qian, Zhihong, editor, Jabbar, M.A., editor, Cheung, Simon K. S., editor, and Li, Xiaolong, editor
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- 2023
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66. Single-atom vibrational spectroscopy with chemical-bonding sensitivity
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Xu, Mingquan, Bao, De-Liang, Li, Aowen, Gao, Meng, Meng, Dongqian, Li, Ang, Du, Shixuan, Su, Gang, Pennycook, Stephen J., Pantelides, Sokrates T., and Zhou, Wu
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- 2023
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67. Research progress on mechanisms of ischemic stroke: Regulatory pathways involving Microglia
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Gao, Xin, Su, Gang, Chai, Miao, Shen, Minghui, Hu, Zhenzhen, Chen, Wei, Gao, Juan, Li, Ruixin, Ma, Tianfei, An, Yang, and Zhang, Zhenchang
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- 2024
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68. Calculated Effects of Vacancy and Ti-doping in 2D Janus MoSSe for Photocatalysis
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Zhao, Yi-Ming, Ren, Pengju, Ma, Xing-Yu, Lewis, James P., Yan, Qing-Bo, and Su, Gang
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Condensed Matter - Materials Science - Abstract
Two-dimensional (2D) Janus transitional metal dichalcogenides (TMDCs) have great potential for photocatalytic water splitting due to their novel properties induced by the unique out-of-plane asymmetric structures. Here, we systematically investigate the geometric, electronic and optical properties of 2D Janus MoSSe with titanium doping and vacancies to explore their synergistic effects on photocatalytic activity. We find that there are effective attractions between the substituted or adsorbed Ti atoms and S/Se vacancies. The Ti adatoms dramatically extend the light absorption range to infrared region. The S/Se vacancies coexisting with Ti adatoms will modulate the transition of photo-excited electrons, thereby enhancing the sunlight absorption. The Ti adatoms either existing alone or coexisting with vacancies introduce smaller lattice distortion compared to substituted Ti atoms and these Ti adatoms induce smaller effective mass of charge carriers. The configuration of S vacancy coexisting with Ti adatoms on Se-surface exhibits the most significant synergistic effects and best overall photocatalytic performance. Our work reveals the mechanism and effects induced by doping and vacancies coexisting in 2D Janus TMDCs, also propose a new practical strategy to improve the performance of 2D photocatalysts.
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- 2021
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69. High-Efficient ab initio Bayesian Active Learning Method and Applications in Prediction of Two-dimensional Functional Materials
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Ma, Xing-Yu, Lyu, Hou-Yi, Hao, Kuan-Rong, Zhu, Zhen-Gang, Yan, Qing-Bo, and Su, Gang
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Condensed Matter - Materials Science - Abstract
Beyond the conventional trial-and-error method, machine learning offers a great opportunity to accelerate the discovery of functional materials, but still often suffers from difficulties such as limited materials data and unbalanced distribution of target property. Here, we propose the ab initio Bayesian active learning method that combines active learning and high-throughput ab initio calculations to accelerate prediction of desired functional materials with the ultrahigh efficiency and accuracy. We apply it as an instance to a large family (3,119) of two-dimensional hexagonal binary compounds with unbalanced materials property, and accurately screen out the materials with maximal electric polarization and proper photovoltaic band gaps, respectively, whereas the computational costs are significantly reduced by only calculating a few tenths of possible candidates in comparison to the random search. This approach shows enormous advantages for the cases with unbalanced distributions of target property. It can be readily applied to seek for a broad range of advanced materials.
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- 2021
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70. Topological gimbal phonons in T-carbon
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You, Jing-Yang, Sheng, Xian-Lei, and Su, Gang
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Condensed Matter - Materials Science - Abstract
The topological metal states in electronic systems have been extensively studied, but topological phonons were explored only in few examples so far. Here, we expose for the first time that the topological nodal gimbal phonons, type-I and type-II Weyl phonons are simultaneously present in T-carbon, a recently realized new allotrope of carbon. At about 15.2 THz, we find that there exist three mutually intersecting nodal loops (named as nodal gimbal phonons) around {\Gamma} point, and two pairs of type-I Weyl phonons on the boundary of Brillouin zone around each X point. In addition, there exist three pairs of type-II Weyl phonons at about 14.5 THz around each L point. It is shown that these exotic topological phonons are protected by corresponding symmetries, and lead to topologically nontrivial surface states. Our findings not only afford plenty of intriguing topological phonon states in a simple material like T-carbon but also provide a new platform to study novel properties of topological phonons, which would facilitate further both experimental and theoretical works in future.
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- 2021
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71. Hexagonal Warping Induced Nonlinear Planar Nernst Effect in Nonmagnetic Topological Insulators
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Yu, Xiao-Qin, Zhu, Zhen-Gang, and Su, Gang
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Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We propose theoretically a new effect, i.e. nonlinear planar Nernst effect (NPNE), in nonmagnetic topological insulator (TI) Bi2Te3 in the presence of an in-plane magnetic field. We find that the Nernst current scales quadratically with temperature gradient but linearly with magnetic field and exhibits a cosine dependence of the orientation of the magnetic field with respect to the direction of the temperature gradient. The NPNE has a quantum origin arising from the conversion of a nonlinear transverse spin current to a charge current due to a joint result of hexagonal warping effect, spin-momentum locking, and the time-reversal symmetry breaking induced by the magnetic field., Comment: 11 pages,7 figures
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- 2020
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72. Two-dimensional topological superconductivity candidate in van der Waals layered material
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You, Jing-Yang, Gu, Bo, Su, Gang, and Feng, Yuan Ping
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Condensed Matter - Superconductivity - Abstract
Two-dimensional (2D) topological superconductors are highly desired because they not only offer opportunities for exploring novel exotic quantum physics, but also possesses potential applications in quantum computation. However, there are few reports on 2D superconductors, let alone topological superconductors. Here, we find a 2D monolayer W$_2$N$_3$, which can be exfoliated from its real van der Waals bulk material with much lower exfoliation energy than MoS$_2$, to be a topological metal with exotic topological states at different energy level. Due to the Van Hove singularities, the density of states near Fermi level are high, making the monolayer a compensate metal. Moreover, the monolayer W$_2$N$_3$ is unveiled to be a superconductor with the superconducting transition temperature Tc $\sim$ 22 K and a superconducting gap of about 5 meV based on the anisotropic Migdal-Eliashberg formalism, arising from the strong electron-phonon coupling around the $\Gamma$ point. Because of the strong electron and lattice coupling, the monolayer displays a non-Fermi liquid behavior in its normal states at temperatures lower than 80 K, where the specific heat exhibit T$^3$ behavior and the Wiedemann-Franz law dramatically violates. Our findings not only provide the platform to study the emergent phenomena in 2D topological superconductors, but also open a door to discover more 2D high-temperature topological superconductors in van der Waals materials.
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- 2020
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73. P-orbital magnetic topological states on square lattice
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You, Jing-Yang, Gu, Bo, and Su, Gang
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Condensed Matter - Materials Science - Abstract
Honeycomb or triangular lattices were extensively studied and thought to be proper platforms for realizing quantum anomalous Hall effect (QAHE), where magnetism is usually caused by d orbitals of transition metals. Here we propose that square lattice can host three magnetic topological states, including the fully spin polarized nodal loop semimetal, QAHE and topologically trivial ferromagnetic semiconductor, in terms of the symmetry and k$\cdot$p model analyses that are materials-independent. A phase diagram is presented. We further show that the above three magnetic topological states can be indeed implemented in two-dimensional (2D) materials ScLiCl5, LiScZ5 (Z=Cl, Br), and ScLiBr5, respectively. The ferromagnetism in these 2D materials is microscopically revealed from p electrons of halogen atoms. This present study opens a door to explore the exotic topological states as well as quantum magnetism from p-orbital electrons by means of the materials-independent approach.
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- 2020
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74. Kagome quantum anomalous Hall effect with high Chern number and large band gap
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Zhang, Zhen, You, Jing-Yang, Ma, Xing-Yu, Gu, Bo, and Su, Gang
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Condensed Matter - Materials Science - Abstract
Due to the potential applications in the low-power-consumption spintronic devices, the quantum anomalous Hall effect (QAHE) has attracted tremendous attention in past decades. However, up to now, QAHE was only observed experimentally in topological insulators with Chern numbers C= 1 and 2 at very low temperatures. Here, we propose three novel two-dimensional stable kagome ferromagnets Co3Pb3S2, Co3Pb3Se2and Co3Sn3Se2that can realize QAHE with high Chern number of |C|=3. Monolayers Co3Pb3S2, Co3Pb3Se2 and Co3Sn3Se2 possess the large band gap of 70, 77 and 63 meV with Curie temperature TC of 51, 42 and 46 K, respectively. By constructing a heterostructure Co3Sn3Se2/MoS2, its TC is enhanced to 60 K and the band gap keeps about 60 meV due to the tensile strain of 2% at the interface. For the bilayer compound Co6Sn5Se4, it becomes a half-metal, with a relatively flat plateau in its anomalous Hall conductivity corresponding to |C| = 3 near the Fermi level. Our results provide new topological nontrivial systems of kagome ferromagnetic monolayers and heterostructrues possessing QAHE with high Chern number |C| = 3 and large band gaps., Comment: 7 pages, 7 figures
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- 2020
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75. Microscopic mechanism of high-temperature ferromagnetism in Fe, Mn, and Cr-doped InSb, InAs, and GaSb magnetic semiconductors
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You, Jing-Yang, Gu, Bo, Maekawa, Sadamichi, and Su, Gang
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Condensed Matter - Materials Science - Abstract
In recent experiments, high Curie temperatures Tc above room temperature were reported in ferromagnetic semiconductors Fe-doped GaSb and InSb, while low Tc between 20 K to 90 K were observed in some other semiconductors with the same crystal structure, including Fe-doped InAs and Mn-doped GaSb, InSb, and InAs. Here we study systematically the origin of high temperature ferromagnetism in Fe, Mn, Cr-doped GaSb, InSb, and InAs magnetic semiconductors by combining the methods of density functional theory and quantum Monte Carlo. In the diluted impurity limit, the calculations show that the impurities Fe, Mn, and Cr have similar magnetic correlations in the same semiconductors. Our results suggest that high (low) Tc obtained in these experiments mainly comes from high (low) impurity concentrations. In addition, our calculations predict the ferromagnetic semiconductors of Cr-doped InSb, InAs, and GaSb that may have possibly high Tc. Our results show that the origin of high Tc in (Ga,Fe)Sb and (In,Fe)Sb is not due to the carrier induced mechanism because Fe3+ does not introduce carriers.
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- 2020
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76. Voting Data-Driven Regression Learning for Discovery of Functional Materials and Applications to Two-Dimensional Ferroelectric Materials
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Ma, Xing-Yu, Lyu, Hou-Yi, Dong, Xue-Juan, Zhang, Zhen, Hao, Kuan-Rong, Yan, Qing-Bo, and Su, Gang
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Condensed Matter - Materials Science - Abstract
Regression machine learning is widely applied to predict various materials. However, insufficient materials data usually leads to a poor performance. Here, we develop a new voting data-driven method that could generally improve the performance of regression learning model for accurately predicting properties of materials. We apply it to investigate a large family (2135) of two-dimensional hexagonal binary compounds focusing on ferroelectric properties and find that the performance of the model for electric polarization is indeed greatly improved, where 38 stable ferroelectrics with out-of-plane polarization including 31 metals and 7 semiconductors are screened out. By an unsupervised learning, actionable information such as how the number and orbital radius of valence electrons, ionic polarizability, and electronegativity of constituent atoms affect polarization was extracted. Our voting data-driven method not only reduces the size of materials data for constructing a reliable learning model but also enables to make precise predictions for targeted functional materials., Comment: 22 pages, 5 figures
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- 2020
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77. Electric field induced topological phase transition and large enhancements of spin-orbit coupling and Curie temperature in two-dimensional ferromagnetic semiconductors
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You, Jing-Yang, Dong, Xue-Juan, Gu, Bo, and Su, Gang
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Condensed Matter - Materials Science - Abstract
Tuning topological and magnetic properties of materials by applying an electric field is widely used in spintronics. In this work, we find a topological phase transition from topologically trivial to nontrivial states at an external electric field of about 0.1 V/A in MnBi$_2$Te$_4$ monolayer that is a topologically trivial ferromagnetic semiconductor. It is shown that when electric field increases from 0 to 0.15 V/A, the magnetic anisotropy energy (MAE) increases from about 0.1 to 6.3 meV, and the Curie temperature Tc increases from 13 to about 61 K. The increased MAE mainly comes from the enhanced spin-orbit coupling due to the applied electric field. The enhanced Tc can be understood from the enhanced $p$-$d$ hybridization and decreased energy difference between $p$ orbitals of Te atoms and $d$ orbitals of Mn atoms. Moreover, we propose two novel Janus materials MnBi$_2$Se$_2$Te$_2$ and MnBi$_2$S$_2$Te$_2$ monolayers with different internal electric polarizations, which can realize quantum anomalous Hall effect (QAHE) with Chern numbers $C$=1 and $C$=2, respectively. Our study not only exposes the electric field induced exotic properties of MnBi2Te4 monolayer, but also proposes novel materials to realize QAHE in ferromagnetic Janus semiconductors with electric polarization., Comment: 7 pages, 5 figures
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- 2020
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78. Visual configuration segmentation of quantum states for phase identification in many-body systems
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Yang, Yuan, Wang, Zhengchuan, Ran, Shi-Ju, and Su, Gang
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Condensed Matter - Strongly Correlated Electrons - Abstract
Artificial intelligence provides an unprecedented perspective for studying phases of matter in condensed-matter systems. Image segmentation is a basic technique of computer vision that belongs to a branch of artificial intelligence. In this work, we propose a segmentation scheme named visual configuration segmentation (VCS) to unveil quantum phases and quantum phase transitions in many-body systems. By encoding the information of renormalized quantum states into a color image and segmenting the color image through the VCS, the renormalized quantum states can be visualized, from which quantum phase transitions can be revealed and the corresponding critical points can be identified. Our scheme is benchmarked on several strongly correlated spin systems, which does not depend on the priori knowledge of order parameters of quantum phases. This demonstrates the potential to disclose the underlying structure of quantum phases by the techniques of computer vision., Comment: 10 pages, 6+4 figures
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- 2020
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79. Great enhancement of Curie temperature and magnetic anisotropy in two-dimensional van der Waals magnetic semiconductor heterostructures
- Author
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Xuejuan-Dong, Jingyang-You, Zhang, Zheng, Gu, Bo, and Su, Gang
- Subjects
Condensed Matter - Materials Science - Abstract
In two-dimensional (2D) magnetic systems, large magnetic anisotropy is needed to stabilize the magnetic order according to Mermin-Wagner theorem. Based on density functional theory (DFT) calculations, we propose that the magnetic anisotropic energy (MAE) of 2D ferromagnetic (FM) semiconductors can be strongly enhanced in van der Waals heterostructures by attaching a nonmagnetic semiconductor monolayer with large spin-orbit coupling. We studied Cr2Ge2Te6/PtSe2 bilayer heterostructures, where each layer has been realized in recent experiments. The DFT calculations show that the MAE of Cr2Ge2Te6/PtSe2 is enhanced by 70%, and the Curie temperature TC is increased far beyond room temperature. A model Hamiltonian is suggested to analyze the DFT results, showing that both the Dzyaloshinskii-Moriya interaction and the single-ion anisotropy contribute to the enhancement of the MAE. Based on the superexchange picture, we find that the decreased energy difference between 3d orbitals of Cr and 5p orbitals of Te contributes partially to the increase of TC. Our present work indicates a promising way to enhance the MAE and TC by constructing van der Waals semiconductor heterostructures, which will inspire further studies on the 2D magnetic semiconductor systems., Comment: 10 pages, 5 figures
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- 2020
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80. Toward understanding physical origin of 2175{\AA} extinction bump in interstellar medium
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Ma, Xing-Yu, Zhu, Yan-Yan, Yan, Qing-Bo, You, Jing-Yang, and Su, Gang
- Subjects
Astrophysics - Astrophysics of Galaxies - Abstract
The 2175 {\AA} ultraviolet (UV) extinction bump in interstellar medium (ISM) of the Milky Way was discovered in 1965. After intensive exploration of more than a half century, however, its exact origin still remains a big conundrum that is being debated. Here we propose a mixture model by which the extinction bump in ISM is argued possibly relevant to the clusters of hydrogenated T-carbon (HTC) molecules (C40H16) that have intrinsically a sharp absorption peak at the wavelength 2175 {\AA}. By linearly combining the calculated absorption spectra of HTC mixtures, graphite, MgSiO3 and Fe2SiO4, we show that the UV extinction curves of optional six stars can be nicely fitted. This present work poses an alternative explanation toward understanding the physical origin of the 2175 {\AA} extinction bump in ISM of the Milky Way., Comment: Monthly Notices of the Royal Astronomical Society accepted
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- 2020
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81. Visualizing Quantum Phases And Identifying Quantum Phase Transitions By Nonlinear Dimensionality Reduction
- Author
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Yang, Yuan, Sun, Zheng-Zhi, Ran, Shi-Ju, and Su, Gang
- Subjects
Condensed Matter - Strongly Correlated Electrons - Abstract
Identifying quantum phases and phase transitions is key to understand complex phenomena in statistical physics. In this work, we propose an unconventional strategy to access quantum phases and phase transitions by visualization based on the distribution of ground states in Hilbert space. By mapping the quantum states in Hilbert space onto a two-dimensional feature space using an unsupervised machine learning method, distinct phases can be directly specified and quantum phase transitions can be well identified. Our proposal is benchmarked on gapped, critical, and topological phases in several strongly correlated spin systems. As this proposal directly learns quantum phases and phase transitions from the distributions of the quantum states, it does not require priori knowledge of order parameters of physical systems, which thus indicates a perceptual route to identify quantum phases and phase transitions particularly in complex systems by visualization through learning., Comment: 11 pages, 10 figures
- Published
- 2020
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82. Large Family of Two-Dimensional Ferroelectric Metals Discovered via Machine Learning
- Author
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Ma, Xing-Yu, Lyu, Hou-Yi, Hao, Kuan-Rong, Zhao, Yi-Ming, Qian, Xiaofeng, Yan, Qing-Bo, and Su, Gang
- Subjects
Condensed Matter - Materials Science - Abstract
Ferroelectricity and metallicity are usually believed not to coexist because conducting electrons would screen out static internal electric fields. In 1965, Anderson and Blount proposed the concept of 'ferroelectric metal', however, it is only until recently that very rare ferroelectric metals were reported. Here, by combining high-throughput ab initio calculations and data-driven machine learning method with new electronic orbital based descriptors, we systematically investigated a large family (2,964) of two-dimensional (2D) bimetal phosphates, and discovered 60 stable ferroelectrics with out-of-plane polarization, including 16 ferroelectric metals and 44 ferroelectric semiconductors that contain seven multiferroics. The ferroelectricity origins from spontaneous symmetry breaking induced by the opposite displacements of bimetal atoms, and the full-d-orbital coinage metal elements cause larger displacements and polarization than other elements. For 2D ferroelectric metals, the odd electrons per unit cell without spin polarization may lead to a half-filled energy band around Fermi level and is responsible for the metallicity. It is revealed that the conducting electrons mainly move on a single-side surface of the 2D layer, while both the ionic and electric contributions to polarization come from the other side and are vertical to the above layer, thereby causing the coexistence of metallicity and ferroelectricity. Van der Waals heterostructures based on ferroelectric metals may enable the change of Schottky barrier height or the Schottky-Ohmic contact type and induce a dramatic change of their vertical transport properties. Our work greatly expands the family of 2D ferroelectric metals and will spur further exploration of 2D ferroelectric metals., Comment: 28 pages, 5 figures, 1 table
- Published
- 2020
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83. Superconductivity in sodium-doped T-carbon
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You, Jing-Yang, Gu, Bo, and Su, Gang
- Subjects
Condensed Matter - Superconductivity - Abstract
T-carbon has been proposed as a new carbon allotrope in 2011, which was successfully synthesized in recent experiments. Because of its fluffy structure, several kinds of atoms can be intercalated into T-carbon, making it a versatile candidate in various applications such as hydrogen storage, perovskite solar cells, lithium ion batteries, thermoelectrics, photocatalyst, etc. Here we show that superconductivity can appear in Na-doped T-carbon with superconducting transition temperature Tc of 11 K at ambient pressure, and Tc can be enhanced to 19 K under pressure of 14 GPa, which results from an enhancement of the electron-phonon coupling due to the shift of the phonon spectral weight to lower frequencies with the increase of pressure. The calculations on specific heat and electrical and thermal conductivities show that the normal state of the Na-doped T-carbon superconductor reveals a non-Fermi liquid behavior. The prediction of superconductivity in Na-doped T-carbon would spur great interest both experimentally and theoretically to explore novel carbon-based superconductors.
- Published
- 2020
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84. Tangent-Space Gradient Optimization of Tensor Network for Machine Learning
- Author
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Sun, Zheng-zhi, Ran, Shi-ju, and Su, Gang
- Subjects
Computer Science - Machine Learning ,Condensed Matter - Disordered Systems and Neural Networks ,Statistics - Machine Learning - Abstract
The gradient-based optimization method for deep machine learning models suffers from gradient vanishing and exploding problems, particularly when the computational graph becomes deep. In this work, we propose the tangent-space gradient optimization (TSGO) for the probabilistic models to keep the gradients from vanishing or exploding. The central idea is to guarantee the orthogonality between the variational parameters and the gradients. The optimization is then implemented by rotating parameter vector towards the direction of gradient. We explain and testify TSGO in tensor network (TN) machine learning, where the TN describes the joint probability distribution as a normalized state $\left| \psi \right\rangle $ in Hilbert space. We show that the gradient can be restricted in the tangent space of $\left\langle \psi \right.\left| \psi \right\rangle = 1$ hyper-sphere. Instead of additional adaptive methods to control the learning rate in deep learning, the learning rate of TSGO is naturally determined by the angle $\theta $ as $\eta = \tan \theta $. Our numerical results reveal better convergence of TSGO in comparison to the off-the-shelf Adam., Comment: 5 pages, 4 figures
- Published
- 2020
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85. Antiferromagnetic and Electric Polarized States in Two-Dimensional Janus Semiconductor Fe2Cl3I3
- Author
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Zhang, Zhen, You, Jing-Yang, Gu, Bo, and Su, Gang
- Subjects
Condensed Matter - Materials Science - Abstract
Two-dimensional (2D) Janus semiconductors with mirror asymmetry can introduce novel properties, such as large spin-orbit coupling (SOC) and normal piezoelectric polarization, which have attracted a great interest for their potential applications. Inspired by the recently fabricated 2D ferromagnetic (FM) semiconductor CrI3, a stable 2D (in x-y plane) antiferromagnetic (AFM) Janus semiconductor Fe2Cl3I3 with normal sublattice magnetization (m//z) is obtained by density functional theory calculations. By applying a tensile strain, the four magnetic states sequentially occur: AFM with m//z of sublattice, AFM with m//xy of sublattice, FM with m//xy, and FM with m//z. Such novel magnetic phase diagram driven by strain can be well understood by the spin-spin interactions including the third nearest-neighbor hoppings with the single-ion anisotropy, in which the SOC of I atoms is found to play an essential role. In addition, the electric polarization of Fe2Cl3I3 preserves with strain due to the broken inversion symmetry. Our results predict the rare Janus material Fe2Cl3I3 as an example of 2D semiconductors with both spin and charge polarizations, and reveal the highly sensitive strain-controlled magnetic states and magnetization direction, which highlights the 2D magnetic Janus semiconductor as a new platform to design spintronic materials., Comment: 8 figures
- Published
- 2020
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86. Unidirectional Seebeck effect in magnetic topological insulators
- Author
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Yu, Xiao-Qin, Zhu, Zhen-Gang, and Su, Gang
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We theoretically investigate the temperature gradient-dependent or unidirectional Seebeck effect (USE) in a magnetic/ nonmagnetic topological insulator (TI) heterostructure with in-plane magnetization in terms of the semiclassical electron dynamics and Fermi golden rule. The USE has a quantum origin arising from the magnon asymmetric scattering of surface Dirac electrons on TI. We discuss the USE in the heterostructures, Cr$_{x}$(Bi$_{1-y}$Sb$_y$)$_{2-x}$Te$_{3}$/ (Bi$_{1-y}$Sb$_{y})_2$Te$_{3}$. The USE exhibits $\cos\phi$-dependence (measured from $y$-direction) on the orientation of magnetization. It's found that the sign of USE stays unchanged when the system is transferred from $p$-doping to $n$-doping. The USE shows on inverse-linearly temperature dependent at high temperature., Comment: 11 pages, 4 figures
- Published
- 2019
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87. Molecular Mechanism of the Protective Effects of M2 Microglia on Neurons: A Review Focused on Exosomes and Secretory Proteins
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Chai, Miao, Su, Gang, Gao, Juan, Chen, Wei, Wu, Qionghui, Dong, Ying, Wang, He, Chen, Deyi, Li, Yonghong, Gao, Xin, Li, Ruixin, Ma, Tianfei, and Zhang, Zhenchang
- Published
- 2022
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88. Exposure to multiple metals in adults and diabetes mellitus: a cross-sectional analysis
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Wu, Zhen, Guan, Tong, Cai, Dandan, and Su, Gang
- Published
- 2022
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89. Identification of the shared gene signatures between pulmonary fibrosis and pulmonary hypertension using bioinformatics analysis
- Author
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Hui Zhao, Lan Wang, Yi Yan, Qin-Hua Zhao, Jing He, Rong Jiang, Ci-Jun Luo, Hong-Ling Qiu, Yu-Qing Miao, Su-Gang Gong, Ping Yuan, and Wen-Hui Wu
- Subjects
pulmonary fibrosis ,pulmonary hypertension ,WGCNA ,differential gene analysis ,T cells CD4 ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Pulmonary fibrosis (PF) and pulmonary hypertension (PH) have common pathophysiological features, such as the significant remodeling of pulmonary parenchyma and vascular wall. There is no effective specific drug in clinical treatment for these two diseases, resulting in a worse prognosis and higher mortality. This study aimed to screen the common key genes and immune characteristics of PF and PH by means of bioinformatics to find new common therapeutic targets. Expression profiles are downloaded from the Gene Expression Database. Weighted gene co-expression network analysis is used to identify the co-expression modules related to PF and PH. We used the ClueGO software to enrich and analyze the common genes in PF and PH and obtained the protein–protein interaction (PPI) network. Then, the differential genes were screened out in another cohort of PF and PH, and the shared genes were crossed. Finally, RT-PCR verification and immune infiltration analysis were performed on the intersection genes. In the result, the positive correlation module with the highest correlation between PF and PH was determined, and it was found that lymphocyte activation is a common feature of the pathophysiology of PF and PH. Eight common characteristic genes (ACTR2, COL5A2, COL6A3, CYSLTR1, IGF1, RSPO3, SCARNA17 and SEL1L) were gained. Immune infiltration showed that compared with the control group, resting CD4 memory T cells were upregulated in PF and PH. Combining the results of crossing characteristic genes in ImmPort database and RT-PCR, the important gene IGF1 was obtained. Knocking down IGF1 could significantly reduce the proliferation and apoptosis resistance in pulmonary microvascular endothelial cells, pulmonary smooth muscle cells, and fibroblasts induced by hypoxia, platelet-derived growth factor-BB (PDGF-BB), and transforming growth factor-β1 (TGF-β1), respectively. Our work identified the common biomarkers of PF and PH and provided a new candidate gene for the potential therapeutic targets of PF and PH in the future.
- Published
- 2023
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90. Accelerated Discovery of Two-Dimensional Optoelectronic Octahedral Oxyhalides via High-Throughput Ab Initio Calculations and Machine Learning
- Author
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Ma, Xing-Yu, Lewis, James P., Yan, Qing-Bo, and Su, Gang
- Subjects
Condensed Matter - Materials Science - Abstract
Traditional trial-and-error methods are obstacles for large-scale searching of new optoelectronic materials. Here, we introduce a method combining high-throughput ab initio calculations and machine-learning approaches to predict two-dimensional octahedral oxyhalides with improved optoelectronic properties. We develop an effective machine-learning model based on an expansive dataset generated from density functional calculations including the geometric and electronic properties of 300 two-dimensional octahedral oxyhalides. Our model accelerates the screening of potential optoelectronic materials of 5,000 two-dimensional octahedral oxyhalides. The distorted stacked octahedral factors proposed in our model play essential roles in the machine-learning prediction. Several potential two-dimensional optoelectronic octahedral oxyhalides with moderate band gaps, high electron mobilities, and ultrahigh absorbance coefficients are successfully hypothesized., Comment: The Journal of Physical Chemistry Letters accepted
- Published
- 2019
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- View/download PDF
91. Two-dimensional magnetic semiconductors with room Curie temperatures
- Author
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You, Jing-Yang, Zhang, Zhen, Dong, Xue-Juan, Gu, Bo, and Su, Gang
- Subjects
Condensed Matter - Materials Science - Abstract
We propose two-dimensional (2D) Ising-type ferromagnetic semiconductors TcSiTe3, TcGeSe3, and TcGeTe3 with high Curie temperatures around 200-0500 K. Owing to large spin-orbit couplings, the large magnetocrystalline anisotropy energy (MAE), large anomalous Hall conductivity, and large magneto-optical Kerr effect were discovered in these intriguing 2D materials. By comparing all possible 2D MGeTe3 materials (M = 3d, 4d, 5d transition metals), we found a large orbital moment around 0.5 $\mu$B per atom and a large MAE for TcGeTe3. The large orbital moments are revealed to be from the comparable crystal fields and electron correlations in these Tc-based 2D materials. The microscopic mechanism of the high Curie temperature is also addressed. Our findings reveal the unique magnetic behaviors of 2D Tc-based materials and present a family of 2D ferromagnetic semiconductors with large MAE and Kerr rotation angles that would have wide applications in designing spintronic devices.
- Published
- 2019
- Full Text
- View/download PDF
92. Flat Band and Hole-induced Ferromagnetism in a Novel Carbon Monolayer
- Author
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You, Jing-Yang, Gu, Bo, and Su, Gang
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
In recent experiments, superconductivity and correlated insulating states were observed in twisted bilayer graphene (TBG) with small magic angles, which highlights the importance of the flat bands near Fermi energy. However, the moir\'e pattern of TBG consists of more than ten thousand carbon atoms that is not easy to handle with conventional methods. By density functional theory calculations, we obtain a flat band at E$_F$ in a novel carbon monolayer coined as cyclicgraphdiyne with the unit cell of eighteen atoms. By doping holes into cyclicgraphdiyne to make the flat band partially occupied, we find that cyclicgraphdiyne with 1/8, 1/4, 3/8 and 1/2 hole doping concentration shows ferromagnetism (half-metal) while the case without doping is nonmagnetic, indicating a hole-induced nonmagnetic-ferromagnetic transition. The calculated conductivity of cyclicgraphdiyne with 1/8, 1/4 and 3/8 hole doping concentration is much higher than that without doping or with 1/2 hole doping. These results make cyclicgraphdiyne really attractive. By studying several carbon monolayers, we find that a perfect flat band may occur in the lattices with both separated or corner-connected triangular motifs with only including nearest-neighboring hopping of electrons, and the dispersion of flat band can be tuned by next-nearest-neighboring hopping. Our results shed insightful light on the formation of flat band in TBG. The present study also poses an alternative way to manipulate magnetism through doping flat band in carbon materials.
- Published
- 2019
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93. Quantum Compressed Sensing with Unsupervised Tensor-Network Machine Learning
- Author
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Ran, Shi-Ju, Sun, Zheng-Zhi, Fei, Shao-Ming, Su, Gang, and Lewenstein, Maciej
- Subjects
Statistics - Machine Learning ,Condensed Matter - Strongly Correlated Electrons ,Computer Science - Machine Learning ,Quantum Physics - Abstract
We propose tensor-network compressed sensing (TNCS) by combining the ideas of compressed sensing, tensor network (TN), and machine learning, which permits novel and efficient quantum communications of realistic data. The strategy is to use the unsupervised TN machine learning algorithm to obtain the entangled state $|\Psi \rangle$ that describes the probability distribution of a huge amount of classical information considered to be communicated. To transfer a specific piece of information with $|\Psi \rangle$, our proposal is to encode such information in the separable state with the minimal distance to the measured state $|\Phi \rangle$ that is obtained by partially measuring on $|\Psi \rangle$ in a designed way. To this end, a measuring protocol analogous to the compressed sensing with neural-network machine learning is suggested, where the measurements are designed to minimize uncertainty of information from the probability distribution given by $|\Phi \rangle$. In this way, those who have $|\Phi \rangle$ can reliably access the information by simply measuring on $|\Phi \rangle$. We propose q-sparsity to characterize the sparsity of quantum states and the efficiency of the quantum communications by TNCS. The high q-sparsity is essentially due to the fact that the TN states describing nicely the probability distribution obey the area law of entanglement entropy. Testing on realistic datasets (hand-written digits and fashion images), TNCS is shown to possess high efficiency and accuracy, where the security of communications is guaranteed by the fundamental quantum principles., Comment: 5+6 pages, 3+6 figures. Essential changes and new data were added to this new version
- Published
- 2019
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94. Molecular monolayer stabilizer for multilayer 2D materials
- Author
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Su, Cong, Yin, Zongyou, Yan, Qing-Bo, Wang, Zegao, Lin, Hongtao, Sun, Lei, Xu, Wenshuo, Yamada, Tetsuya, Ji, Xiang, Zettsu, Nobuyuki, Teshima, Katsuya, Warner, Jamie H., Dincă, Mircea, Hu, Juejun, Dong, Mingdong, Su, Gang, Kong, Jing, and Li, Ju
- Subjects
Physics - Applied Physics ,Condensed Matter - Materials Science - Abstract
2D van der Waals materials have rich and unique functional properties, but many are susceptible to corrosion under ambient conditions. Here we show that linear alkylamines are highly effective in protecting the optoelectronic properties of these materials such as black phosphorous (BP) and transitional metal dichalcogenides. As a representative example, n-hexylamine can be applied in the form of thin molecular monolayers on BP flakes with less-than-2nm thickness and can prolong BP's lifetime from a few hours to several weeks and even months in ambient environments. Characterizations combined with our theoretical analysis show that the thin monolayers selectively sift out water molecules, forming a drying layer to achieve the passivation of the protected 2D materials. The monolayer coating is also stable in air, hydrogen annealing, and organic solvents, but can be removed by certain organic acids.
- Published
- 2019
95. Reentrance of Topological Phase in Spin-1 Frustrated Heisenberg Chain
- Author
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Yang, Yuan, Ran, Shi-Ju, Chen, Xi, Sun, Zhengzhi, Gong, Shou-Shu, Wang, Zhengchuan, and Su, Gang
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science ,Physics - Computational Physics - Abstract
For the Haldane phase, the magnetic field usually tends to break the symmetry and drives the system into a topologically trivial phase. Here, we report a novel reentrance of the Haldane phase at zero temperature in the spin-1 antiferromagnetic Heisenberg model on sawtooth chain. A partial Haldane phase is induced by the magnetic field, which is the combination of the Haldane state in one sublattice and a ferromagnetically ordered state in the other sublattice. Such a partial topological order is a result of the zero-temperature entropy due to quantum fluctuations caused by geometrical frustration., Comment: 9 pages, 4+7 figures
- Published
- 2019
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96. Two-Dimensional Room Temperature Ferromagnetic Semiconductors with Quantum Anomalous Hall Effect
- Author
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You, Jing-Yang, Zhang, Zhen, Gu, Bo, and Su, Gang
- Subjects
Condensed Matter - Materials Science - Abstract
To obtain room temperature ferromagnetic semiconductors is one of big challenges in science, and also premises essentially to realize room temperature quantum anomalous Hall effect (QAHE), both of which are quite expected for a long time. Here we report that, based on first-principles calculations, PdBr3, PtBr3, PdI3 and PtI3 monolayers are ferromagnetic semiconductors with possible high temperature QAHE. Monte Carlo simulations give Curie temperatures 350 K and 375 K for PdBr3 and PtBr3 monolayers, respectively. These two-dimensional (2D) materials are Chern insulators. The band gaps of PdBr3 and PtBr3 are 58.7 meV and 28.1 meV with GGA and 100.8 meV and 45 meV with HSE06, respectively, quite well in favor of observing room temperature QAHE. The large band gaps were unveiled from multi-orbital electron correlations. By carefully checking the stability, PdBr3, PtBr3, and PtI3 monolayers are all predicted to be feasible in experiment. The present work sheds new light on developing promising spintronic devices by using the room temperature ferromagnetic semiconductors, and dissipationless devices by applying room temperature QAHE., Comment: 6 pages, 4 figures
- Published
- 2019
- Full Text
- View/download PDF
97. Exploring T-carbon for Energy Applications
- Author
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Qin, Guangzhao, Hao, Kuan-Rong, Yan, Qing-Bo, Hu, Ming, and Su, Gang
- Subjects
Condensed Matter - Materials Science - Abstract
Seeking for next-generation energy sources that are economic, sustainable (renewable), clean (environment-friendly), and abundant in earth is crucial when facing the challenges of energy crisis. There have been numerous studies exploring the possibility of carbon based materials to be utilized in future energy applications. In this paper, we introduce T-carbon, which is a theoretically predicted but recently experimentally synthesized carbon allotrope, as a promising material for next-generation energy applications. It is shown that T-carbon can be potentially used in thermoelectrics, hydrogen storage, lithium ion batteries, \emph{etc}. The challenges, opportunities, and possible directions for future studies of energy applications of T-carbon are also addressed. With the development of more environment-friendly technologies, the promising applications of T-carbon in energy fields would not only produce scientifically significant impact in related fields but also lead to a number of industrial and technical applications., Comment: 9 pages, 3 figures
- Published
- 2019
- Full Text
- View/download PDF
98. Generative Tensor Network Classification Model for Supervised Machine Learning
- Author
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Sun, Zheng-Zhi, Peng, Cheng, Liu, Ding, Ran, Shi-Ju, and Su, Gang
- Subjects
Computer Science - Machine Learning ,Condensed Matter - Strongly Correlated Electrons ,Quantum Physics ,Statistics - Machine Learning - Abstract
Tensor network (TN) has recently triggered extensive interests in developing machine-learning models in quantum many-body Hilbert space. Here we purpose a generative TN classification (GTNC) approach for supervised learning. The strategy is to train the generative TN for each class of the samples to construct the classifiers. The classification is implemented by comparing the distance in the many-body Hilbert space. The numerical experiments by GTNC show impressive performance on the MNIST and Fashion-MNIST dataset. The testing accuracy is competitive to the state-of-the-art convolutional neural network while higher than the naive Bayes classifier (a generative classifier) and support vector machine. Moreover, GTNC is more efficient than the existing TN models that are in general discriminative. By investigating the distances in the many-body Hilbert space, we find that (a) the samples are naturally clustering in such a space; and (b) bounding the bond dimensions of the TN's to finite values corresponds to removing redundant information in the image recognition. These two characters make GTNC an adaptive and universal model of excellent performance., Comment: 7 pages, 5 figures
- Published
- 2019
- Full Text
- View/download PDF
99. Two-dimensional Weyl Half Semimetal and Tunable Quantum Anomalous Hall Effect in Monolayer PtCl$_{3}$
- Author
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You, Jing-Yang, Chen, Cong, Zhang, Zhen, Sheng, Xian-Lei, Yang, Shengyuan A., and Su, Gang
- Subjects
Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We propose a new topological quantum state of matter---the two-dimensional (2D) Weyl half semimetal (WHS), which features 2D Weyl points at Fermi level belonging to a single spin channel, such that the low-energy electrons are described by fully spin-polarized 2D Weyl fermions. We predict its realization in the ground state of monolayer PtCl$_3$. We show that the material is a half metal with an in-plane magnetization, and its Fermi surface consists of a pair of fully spin-polarized Weyl points protected by a mirror symmetry, which are robust against spin-orbit coupling. Remarkably, we show that the WHS state is a critical state at the topological phase transition between two quantum anomalous Hall insulator phases with opposite Chern numbers, such that a switching between quantum anomalous Hall states can be readily achieved by rotating the magnetization direction. Our findings demonstrate that WHS offers new opportunity to control the chiral edge channels, which will be useful for designing new topological electronic devices., Comment: 5 pages, 4 figures
- Published
- 2019
- Full Text
- View/download PDF
100. Topological Nonlinear Anomalous Nersnt Effect in Strained Transition Metal Dichalcogenides
- Author
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Yu, Xiao-Qin, Zhu, Zhen-Gang, You, Jhih-Shih, Low, Tony, and Su, Gang
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We theoretically analyze the non-linear anomalous Nernst effect as the second-order response of temperature gradient by using the semiclassical framework of electron dynamics. We find that a non-linear current can be generated transverse to the applied temperature gradient in time-reversal-symmetry materials with broken inversion symmetry. This effect has a quantum origin arising from the Berry curvature of states near the Fermi surface. We discuss the non-linear Nernst effect in transition metal dichalcogenides~(TMDCs) under the application of uniaxial strain. In particular, we predict that under fixed chemical potential in TMDCs, the non-linear Nernst current exhibits a transition from $\textbf{j}^\text{dip}_\text{A}\sim T^{-2}$ temperature dependence in low temperature regime to a linear $T$-dependence in high temperature., Comment: 5 pages, 2 figures
- Published
- 2019
- Full Text
- View/download PDF
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