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Isotropic power-law decay indices of LDOS oscillations induced by line defects in monolayer black phosphorus

Physical Review B 2025年第16期111卷 165419-165419页

作者： Xiaoying Zhou Qianwen Ou Wang Chen Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and Electronics Science Hunan University of Science and Technology Xiangtan 411201 China Department of Physics Hunan Normal University Changsha 410081 China

Due to its anisotropic crystal structure, the electronic, optical, and thermal properties of two-dimensional black phosphorus (BP) exhibit significant anisotropy. In this study, we investigate the oscillations of the local density of states (LDOS) near a line defect in monolayer BP. Utilizing the two-band effective k·p Hamiltonian, we numerically calculate the LDOS using the transfer matrix method and analytically derive the power-law decay indices of the LDOS oscillation patterns based on the stationary phase approximation. We find that the power-law decay indices of the LDOS oscillation patterns are always −1/2 irrespective of the orientation of the defects, indicating a remarkable isotropic behavior. While, the magnitude and period of the LDOS patterns are highly sensitive to the orientation of the line defect, which serves as a manifestation of the anisotropy inherent in BP. These results highlight a unique aspect of BP and are also applicable to commensurate multilayer BP, as they share a similar Hamiltonian to that of the monolayer.

关键词： Crystal orientation

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New axion contribution to the two-photon decays of neutral pions

arXiv

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arXiv 2025年

作者： Lu, Zhen-Yan Huang, Yang Cheng, Ji-Gui Lu, Qi Wang, Shu-Peng Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and Electronics Hunan University of Science and Technology Xiangtan411201 China School of Physics Beihang University Beijing102206 China

The presence of axions introduces new diagrams at one-loop order to the two-photon decays of the neutral pion through axion-pion mixing. In this work, we calculate this correction, missing in all current calculations, in the framework of SU(2) chiral perturbation theory. We show that the correction is proportional to the axion-photon coupling and the square of axion mass, which in turn is strongly suppressed by the axion decay constant for the classical space window but may not be negligible for the QCD axion in the MeV or even larger mass range. On the other hand, in combination with the experimental measurement of the decay width of π0 → γγ process, this result rules out the standard QCD axion as an explanation for the possible discrepancy between the chiral perturbation theory prediction and the experimental data. © 2025, CC BY-NC-SA.

关键词： Photons

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Revisiting the search for dark matter subhalos using the Fermi-LAT 4FGL-DR4 catalog

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Physical Review D 2025年第2期111卷 023033-023033页

作者： Ji-Gui Cheng Le Zou School of Physics and Electronics Hunan University of Science and Technology Xiangtan 411201 China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials Hunan University of Science and Technology Xiangtan 411201 China Department of Physics Xiangtan University Xiangtan 411105 China Key Laboratory of Stars and Interstellar Medium Xiangtan University Xiangtan 411105 China

Numerical simulations suggest that dark matter halos surrounding galaxies host numerous small subhalos, which might be detectable by the Fermi LAT. In this work, we revisit the search for gamma-ray subhalo candidates using the latest Fermi-LAT 4FGL-DR4 catalog. The search is performed by fitting the spectral data of unassociated point sources in the catalog through an unbinned maximum likelihood method. We consider two models in the fitting. One is an empirical function provided by the catalog, and another is a dark matter (DM) model in which DM particles within nearby subhalos annihilate into gamma rays and other Standard Model particles. Based on the fitting results, we identify 32 candidates for which the maximum likelihood value of the DM model fit exceeds that of the empirical function fit. The estimated J-factors of these candidates range from 0.2 to 5.8×1020 GeV2 cm−5, the DM particle masses vary from 30 to 500 GeV, and 12 of them are within the range of [30,80] GeV. Candidate 4FGL J2124.2+1531 is an exception, with a J-factor of 4.52×1021 GeV2 cm−5 and a particle mass of 3108.44 GeV. Interestingly, the identified candidates do not overlap with those reported in previous works, and we discuss the possible reasons for the discrepancy. At the current stage, we cannot rule out the possibility that these candidates are gamma-ray pulsars, and further confirmation through multiband observations is required.

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Polarization-controlled contact barriers enable giant tunneling electroresistance in van der Waals ferroelectric tunnel junctions

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Applied Physics Letters 2025年第16期126卷

作者： Bai, Xueyan Zou, Daifeng Lei, Chihou He, Zhijian Liu, Yunya School of Physics and Electronic Science Hunan University of Science and Technology Xiangtan411201 China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials Hunan Xiangtan411201 China Department of Physics and Engineering University of Scranton ScrantonPA18510 United States Key Laboratory of Low Dimensional Materials and Application Technology Ministry of Education School of Materials Science and Engineering Xiangtan University Xiangtan411105 China

The regulation of tunneling electroresistance (TER) in two-dimensional (2D) ferroelectric tunnel junctions (FTJs) is crucial for their practical applications. In this Letter, we introduce an innovative approach to manipulate TER by altering the interfacial contact barrier through polarization-induced modifications in interface transport properties. A comprehensive analysis of the electronic structures within heterostructures, consisting of a metallic TaSe2 monolayer and a ferroelectric Sc2CO2 layer, uncovers a dual modulation effect of ferroelectricity on both the Schottky barrier height and the interfacial tunneling barrier. This phenomenon substantiates the influence of polarization on charge carrier transport across the interface. Through calculations employing the non-equilibrium Green's function method, we reveal a significant TER ratio ( 2.41 × 10 13 %) in TaSe2/Sc2CO2-based FTJs. Our findings illustrate that distinct tunneling resistance states can be achieved through polarization reversal, as predicted by the proposed mechanism. These insights enhance the understanding of polarization-mediated TER in 2D FTJs and provide a foundation for the design of next-generation electronic devices leveraging 2D ferroelectric materials. © 2025 Author(s).

关键词： Van der Waals forces

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Enhanced phase transformation in BiFeO3 thin films via synergistic pressure and electric field modulation

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Journal of Applied Physics 2025年第18期137卷

作者： Long, Jiemei Yang, Yan Dong, Yangda Bin, Shuping Zhang, Yuan Tan, Congbing Wang, Jinbin Song, Hongjia Zhong, Xiangli School of Materials Science and Engineering Xiangtan University Hunan Xiangtan411105 China Department of Materials Science and Engineering Southern University of Science and Technology Guangdong Shenzhen518055 China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and Electronics Hunan University of Science and Technology Hunan Xiangtan411201 China

In complex multi-field application environments, enhancing the rhombohedral/tetragonal (R/T) phase transition in BiFeO3 (BFO) thin films and making more appearances of R/T morphotropic phase boundaries (MPBs) play a key role in improving the physical properties, such as ferroelectric, piezoelectric, and dielectric, and so on. Therefore, it is particularly important to study the R/T phase transition behavior of the BFO thin films under multi-field conditions. In this paper, the behavior of R/T phase transition in BFO thin films under synergistic modulation of pressure and electric fields is investigated by scanning probe microscopy. Under the condition of pressure-positive voltage synergistic regulation, achieving an R/T MPB with a volume fraction of 35.1% merely requires 3 V, which is lower than the one under a single positive voltage. Under the condition of pressure-negative voltage synergistic regulation, the relationship between the pressure and the voltage is mutual restraint and counterbalance. Under the pressure of above 1.3 μN, the decrease in volume fraction of MPBs is only 1/2 of the one without pressure when the negative voltage is increased from −6 to −10 V. This work provides new ideas and strategies for researching high-performance ferroelectric, piezoelectric, and dielectric devices, holding significant theoretical importance in BFO thin films in complex multi-field application environments. © 2025 Author(s).

关键词： Ferroelectric devices

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Magneto-optical conductivity and circular dichroism in d-wave altermagnets

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Physical Review B 2025年第6期111卷 064428-064428页

作者： Wang Chen Xiaoying Zhou Wen-Kai Lou Kai Chang State Key Laboratory of Semiconductor Physics and Chip Technologies Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China College of Materials Science and Opto-electronic Technology University of Chinese Academy of Sciences Beijing 100049 China Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and Electronics Science Hunan University of Science and Technology Xiangtan 411201 China Center for Quantum Matter School of Physics Zhejiang University Hangzhou 310027 China

We theoretically investigate the Landau levels (LLs) and magneto-optical conductivity of a d-wave altermagnet under a perpendicular magnetic field. Our findings indicate that the LLs, in the absence of a Zeeman field and spin-orbit coupling (SOC), are spin-degenerate and exhibit a linear dependence on both the magnetic field and the level index. Within the framework of linear response theory, the analytical optical transition matrix elements yield isotropic selection rules and anisotropic longitudinal magneto-optical conductivity peaks, regardless of whether SOC is considered. Specifically, in the absence of SOC, only the intraband transition can occur, with the selection rule given by Δn=±1. The spin-resolved longitudinal magneto-optical conductivities without a Zeeman field alternately coincide (Reσxx↑=Reσyy↓ and Reσxx↓=Reσyy↑), resulting in identical spin-resolved Hall magneto-optical conductivities (Imσxy↑=Imσxy↓). In the presence of SOC, both intraband and interband transitions occur, with selection rules of Δn=±1 and ±3. Notably, the magnitude of the magneto-optical conductivities associated with the transition process of Δn=±1 is three orders of magnitude larger than that associated with Δn=±3. This distinctive magneto-optical absorption spectrum clearly reflects the structure of the LLs and leads to strong circular dichroism in the altermagnets. Our results elucidate the magneto-optical properties of altermagnets and can be utilized to determine band parameters at zero magnetic field.

关键词： Dichroism

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Dipole-induced transparency in a cavity-waveguide system with attractive cavity modes

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Physical Review A 2025年第3期111卷 033710-033710页

作者： Zhao-Hui Peng Chun-Xia Jia Yu-Qing Zhang Ying Yang Xiang-Yun Fu Wangjun Lu Le-Man Kuang Hunan Provincial Key Laboratory of Intelligent Sensors and Advanced Sensor Materials and Department of Physics Hunan University of Science and Technology Xiangtan 411201 China Department of Maths and Physics Hunan Institute of Engineering Xiangtan 411104 China Key Laboratory of Low-Dimension Quantum Structures and Quantum Control of Ministry of Education Synergetic Innovation Center for Quantum Effects and Applications and Department of Physics Hunan Normal University Changsha 410081 China Synergetic Innovation Academy for Quantum Science and Technology Zhengzhou University of Light Industry Zhengzhou 450002 China

Dipole-induced transparency (DIT) is one of the most well-known transparency effects in quantum optics and has wide applications in scalable quantum information processing and quantum computation. However, most of the existing literatures only focuses on the DIT effect with coherent dipole-cavity coupling, thus its universality in other types of coupling is still to be clarified. Here, we propose a feasible scheme to realize dissipative dipole-cavity coupling with the assistance of a highly dissipative microcavity, and explicitly exhibit cavity-mode attraction. We then investigate the DIT effect in a cavity-waveguide system with attractive cavity modes and find that it can still be achievable even though the probe light is resonant with two attractive cavity modes. Furthermore, we reveal its underlying transparency mechanism with eigenfrequencies and the effective susceptibility of the dipole-cavity system, and show that its transparency lies in the destructive interference of two attractive cavity modes with splitting damping rates instead of splitting resonance frequencies in coherent coupling. Moreover, we find that the attractive and repulsive phenomena of the effective susceptibility, which also plays an important role in the DIT effect, exist in the dipole-cavity system. Our findings may not only be of importance for gaining a more comprehensive understanding on the DIT effect, but also have potential applications in quantum networks.

关键词： Quantum optics

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Testing the cosmic distance duality relation using Type Ia supernovae and BAO observations

arXiv

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arXiv 2025年

作者： Yang, Fan Fu, Xiangyun Xu, Bing Zhang, Kaituo Huang, Yang Yang, Ying Department of Physics Key Laboratory of Intelligent Sensors and Advanced Sensor Materials Hunan University of Science and Technology Hunan Xiangtan411201 China School of Electrical and Electronic Engineering Anhui Science and Technology University Anhui Bengbu233030 China Department of Physics Anhui Normal University Anhui Wuhu241000 China

In this work, we propose to utilize the observed ratio of spherically-averaged distance to the sound horizon scale from Baryon Acoustic Oscillation (BAO) data to test the cosmic distance duality relation (CDDR) by comparing the luminosity distances (LDs) obtained from Type Ia supernovae (SNIa) observations with angular diameter distances (ADDs) derived from these ratio measurements, using a cosmological-model-independent method. To match the LDs with the ADDs at the identical redshifts, we employ two methods: a compressed form of the Pantheon sample and a hybrid approach that combines the binning method with an artificial neural network (ANN). The Hubble parameter H(z) at any redshift is reconstructed from the observed Hubble parameter data with the ANN to derive the ADD. To avoid potential biases resulted from the specific prior values of the absolute magnitude MB of SNIa and the sound horizon scale rd from BAO measurements, we introduce the fiducial parameter κ ≡ 10MB/5 rd3/2 and marginalize their impacts by treating them as nuisance parameters with flat prior distributions in our statistical analysis. Subsequently, we update the measurements of ratio of the transverse comoving distance to the sound horizon scale from the latest BAO data released by the Dark Energy Spectroscopic Instrument (DESI) collaboration for CDDR testing. Our results indicate that BAO observation provides a powerful tool for testing the CDDR, independent of both the absolute magnitude MB and sound horizon scale rd, as well as any cosmological model. © 2025, CC BY.

关键词： Supernovae

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Polarized image of an equatorial emitting ring around a rotating braneworld black hole

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European Physical Journal C 2025年第5期85卷 1-12页

作者： Qin, Xin Chen, Songbai Fu, Xiangyun Huang, Yang Jing, Jiliang School of Physics and Electronic Science Hunan University of Science and Technology Xiangtan 411021 China Key Laboratory of Intelligent Sensors and Advanced Sensing Materials of Hunan Province Xiangtan 411021 China Department of Physics Institute of Interdisciplinary Studies Synergetic Innovation Center for Quantum Effects and Applications Hunan Changsha 410081 China Center for Gravitation and Cosmology College of Physical Science and Technology Yangzhou University Yangzhou 225009 China

We have studied the polarized image of an equatorial emitting ring around a rotating braneworld black hole. This black hole possesses a tidal charge parameter b, which describes the effects of the free gravitational field in the bulk on the brane. Results show that the effects of the tidal charge parameter on the polarized image depend on the magnetic field structure, the observer inclination, the velocity of the fluid and the radii of the emitting ring. For a given value of the rotation parameter, the observed polarization intensity increases monotonously with b when the magnetic field lies in the equatorial plane, while it no longer changes monotonically with b when the magnetic field is perpendicular to the equatorial plane. The effect of parameter b on polarized images is similar in both stronger and weaker gravitational fields when the magnetic field is within the equatorial plane, and the differences in polarization vectors for different b become noticeable in stronger gravitational fields. We also probe the effects of b on the Stokes Q-U loops. © The Author(s) 2025.

关键词： Gravitational effects

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Synthesis of Z-Scheme G-C3n4/Zns Heterojunction Photocatalysts with Enhanced Photocatalytic Activity

SSRN

引用

SSRN 2025年

作者： Chai, Yi-Feng Tan, Shengxia Wang, Binglin Guo, Shengwei Jiang, Ru Zhu, ZhongHua Huang, Gui-Fang Huang, Wei-Qing School of Physics and Electronics Science Hunan University of Science and Technology Hunan Xiangtan411201 China Key Laboratory of Intelligent Sensor and Advance Materials of Hunan Province Hunan University of Science and Technology Xiangtan411201 China Department of Applied Physics School of Physics and Electronics Hunan University Changsha410082 China

In the present study, g-C3N4/ZnS nanocomposites with varying volume percentages were fabricated via hydrothermal deposition and then comprehensively characterized employing XRD, SEM, XPS, UV-vis and PL. The photocatalytic capabilities of these g-C3N4/ZnS nanocomposites with different volume proportions were explored by means of degrading MB under visible light irradiation. The degradation rate of 2wt% g-C3N4/ZnS nanocomposites reached 95.75%, which was 6.38 times that of g-C3N4 and 4.76 times that of ZnS. Additionally, after 4 consecutive cycles, the degradation efficiency of the photocatalyst with respect to MB remained at 75.12%, indicating that its binary structure exhibited excellent stability and recovery prospects in the realm of visible light catalysis. The impressive photocatalytic activity of the g-C3N4/ZnS sample may be attributed to its Z-scheme heterojunction, which efficiently transfers and separates charge carriers. The promotion of superoxide radical (•O2-) generation also contributes to the improvement in photocatalytic activity. © 2025, The Authors. All rights reserved.

关键词： Heterojunctions

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