Science China Physics, Mechanics & Astronomy最新文献

{"title":"Field intensity dependence of the dissociative multiple ionization of argon dimers in strong femtosecond laser fields","authors":"Pan Song,&nbsp;Yalei Zhu,&nbsp;Xiaowei Wang,&nbsp;Congsen Meng,&nbsp;Tao Jiang,&nbsp;Zhihui Lv,&nbsp;Dongwen Zhang,&nbsp;Chaochao Qin,&nbsp;Zengxiu Zhao,&nbsp;Jianmin Yuan","doi":"10.1007/s11433-024-2474-x","DOIUrl":"10.1007/s11433-024-2474-x","url":null,"abstract":"<div><p>The dissociative ionization of Ar dimers is investigated in femtosecond laser fields with intensities from 260 to 1020 TW/cm². The three-dimensional momentum and kinetic-energy release of fragmental ions generated from the channels Ar₂²⁺→Ar⁺+Ar⁺, Ar₂³⁺→Ar²⁺+Ar⁺, and Ar₂⁴⁺→Ar²⁺+Ar²⁺ were measured with a cold-target recoil-ion momentum spectrometer. It is shown that the laser intensity significantly modulates the kinetic energies and angular distributions of fragmental ions from dissociative double ionization. Laser-induced charge-transfer following one-site double ionization contributes relatively more to the dissociative double ionization at lower laser intensity. The calculation results of a one-dimensional model based on the WKB approximation suggest that the charge transfer is suppressed at higher laser intensity due to the core polarization effect. In addition, double, triple, and quadruple dissociative ionizations of Ar dimers are accompanied by frustrated-tunneling ionization that increases with the laser intensity.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 12","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11433-024-2474-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142413490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inverse design of quasi-bound states in the continuum metasurface for the polarization independent enhancement of Goos-Hänchen shift","authors":"Zuhai Ma,&nbsp;Youzhi Shi,&nbsp;Yu Chen,&nbsp;Yu Xue,&nbsp;Gan Wan,&nbsp;Chi Zhang,&nbsp;Hui Jing,&nbsp;Le-Man Kuang,&nbsp;Xinxing Zhou","doi":"10.1007/s11433-024-2493-5","DOIUrl":"10.1007/s11433-024-2493-5","url":null,"abstract":"<div><p>Bound states in the continuum (BIC) have been widely researched and applied in optics due to their unique electromagnetic response. However, there are still difficulties in predicting and customizing BIC spectra. To address this issue, we design an efficient combined neural network for highly accurate prediction of quasi-bound states in the continuum (q-BIC) spectrum, as well as for the inverse design of the polarization independent enhancement of the Goos-Hänchen (GH) shift. Firstly, we propose a C₄ symmetric metasurface for achieving q-BIC spectrum and providing the condition of enhanced GH shift. By employing a combined neural network, the intensity, position, shape, and phase of q-BIC spectrum with ultra-narrow resonance can be accurately predicted and on-demand customized, even under a small dataset. Besides, we develop a screening algorithm for the q-BIC spectrum to quickly realize the polarization independent enhancement of GH shift. As an application, an ultra-high sensitivity refractive index sensor has been proposed, whose sensitivity can reach 2.31×10⁷ µm/RIU for TM polarization and 1.03·10⁶ µm/RIU for TE polarization. Therefore, this work brings new solutions for quick prediction of q-BIC spectrum and the development of flexible polarization photonic devices.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 12","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142413612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anisotropic coherence induced nonuniform amplification in N\u0000 +2","authors":"Hongqiang Xie,&nbsp;Qian Zhang,&nbsp;Hongbin Lei,&nbsp;Na Wang,&nbsp;Yuhan Zheng,&nbsp;Zhiming Chen,&nbsp;Guihua Li,&nbsp;Zengxiu Zhao","doi":"10.1007/s11433-024-2491-6","DOIUrl":"10.1007/s11433-024-2491-6","url":null,"abstract":"<div><p>The continuous progress in N<span>\u0000 ⁺₂\u0000 \u0000 </span> lasing recently stimulates a great deal of interest in nonlinear and quantum optics of molecular ions, while a complete description of the ionic polarization is still lacking to date. In this work, we are dedicated to constructing the fundamental ionic polarization theory where several ubiquitous strong-field processes including ionization, electronic couplings and molecular alignment jointly determine the spatial arrangement of ions. With the model, the elusive polarization of N<span>\u0000 ⁺₂\u0000 \u0000 </span> lasing can be well interpreted. Our results show that the different electronic transition rules for strong-field ionization and resonant couplings result in peculiar population distributions of various electronic states of N<span>\u0000 ⁺₂\u0000 \u0000 </span> in space. Meanwhile, the spatial nonuniformity of population distribution can be aggravated or mitigated during field-free evolutions of coherent molecular rotational wave packets. Furthermore, when a follow-up resonant seed pulse interacts with the prepared ionic system, the anisotropic quantum coherence determining the polarization of subsequent N<span>\u0000 ⁺₂\u0000 \u0000 </span> lasing can be established. The qualitative agreement between experiments and simulations confirms the validity of the proposed model. The findings provide critical insights into the polarization and radiation mechanisms of molecular ions constructed via ultrafast laser pulses.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 12","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Self-consistent extraction of photoabsorption time delays in attosecond streak camera","authors":"Yutong Gao,&nbsp;Hongcheng Ni,&nbsp;Andreas Becker,&nbsp;Jian Wu","doi":"10.1007/s11433-024-2452-6","DOIUrl":"10.1007/s11433-024-2452-6","url":null,"abstract":"<div><p>Photoionization can generally be decomposed into a photoabsorption process plus a half-scattering process. The streaking time delay observed in the attosecond streak camera, correspondingly, can be decomposed into a photoabsorption time delay and a continuum time delay. We propose a self-consistent method to account for the potential-laser coupling effect and extract the intrinsic absorption time delay, without invoking an implicit assumption of a constant continuum correction made in previous streaking studies. The concept is based on an iterative technique starting from an initial guess of the absorption time delay and using classical electron trajectories to consistently remove the coupling-induced momentum shift to the streak signal. We show that the self-consistent iterative algorithm converges quickly and is robust against different initial guesses. The method is applied to laser-induced ionization of atoms to obtain the absorption time delay in resonant two-photon ionization and to explore possible time delays in above-threshold ionization. The results confirm an absorption time delay linearly dependent on the ionizing pulse duration in resonant two-photon ionization. The method is also shown to perform better than conventional methods and to identify a small negative absorption time delay (less than 2 attoseconds) in above-threshold ionization.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 12","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coherent emission and attosecond transient absorption of N\u0000 +2\u0000 \u0000 in strong fields","authors":"Qian Zhang,&nbsp;Guangru Bai,&nbsp;Bin Zhang,&nbsp;Jinlei Liu,&nbsp;Hongbin Lei,&nbsp;Xiaowei Wang,&nbsp;Jing Zhao,&nbsp;Zengxiu Zhao","doi":"10.1007/s11433-024-2397-4","DOIUrl":"10.1007/s11433-024-2397-4","url":null,"abstract":"<div><p>The ionic dynamics induced by strong-field ionization are essential to understand the fundamental physics and chemical reactions. By solving the ionization-coupling equation theoretically, we can simultaneously address strong-field ionization and coupling dynamics in ions. By employing the driving pulse at the wavelength of 1580 nm, we show that the <i>B</i>²Σ<span>\u0000 ⁺_<i>u</i>\u0000 \u0000 </span> state of the strong field ionization created N<span>\u0000 ⁺₂\u0000 \u0000 </span> could be populated by polarization effect and five-photon resonance but there is no population inversion between <i>X</i>²Σ<span>\u0000 ⁺_<i>g</i>\u0000 \u0000 </span> and <i>B</i>²Σ<span>\u0000 ⁺_<i>u</i>\u0000 \u0000 </span> states for the nitrogen molecular ions aligning along the laser polarization. In addition, both the ultraviolet supercontinuum and the attosecond transient absorption spectroscopy (ATAS) are calculated to illustrate the characteristics of population and coherence. The Stark shift observed from the transient absorption confirms the origin of ultraviolet supercontinuum. Our results show the evolution of the absorption spectral lineshape, varying from Lorentzian to Fano to inverted Lorentzian and back forth and the optical gain is achieved at 394 eV due to the vibrational coherent dynamics. This study offers valuable insights into the strong-field quantum optics of molecular ions.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 12","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetic properties of soft magnetic composites prepared by gas-atomized glassy powders from a new Fe-based alloy with high glass-forming ability","authors":"Ranbin Wang,&nbsp;Jili Jia,&nbsp;You Wu,&nbsp;Wenhui Guo,&nbsp;Na Chen,&nbsp;Yang Shao,&nbsp;Kefu Yao","doi":"10.1007/s11433-024-2441-3","DOIUrl":"10.1007/s11433-024-2441-3","url":null,"abstract":"<div><p>With a pressing need for high efficiency, low power consumption, and miniaturization of electronics, soft magnetic composites (SMCs) show great potential, especially for applications in key electronic component. However, core loss is still the focused issue for SMCs that hinders their sustainable development and widespread applications. In the present study, high-performance SMCs were fabricated by novel Fe₇₄B₇C₇P₇Si₃Mo₁Cr₁ powders with spherical shape and a fully glassy structure, which were successfully prepared by a gas atomization method. The microstructure and high-frequency magnetic properties of these SMCs were studied in detail. To enhance the soft ferromagnetism, the effects of annealing temperature (<i>T</i>_a) and powder size on their performance were clarified. Increasing <i>T</i>_a up to 703 K not only helps to effectively release internal stress in the powders, but also improves the integrity of the insulation layer structure, which is conducive to decreasing the core loss. In addition, reducing the powder size contributes to the overall performance enhancement. Prepared from the powders with the smallest mean particle size and annealed at 703 K, the SMC exhibits optimum property combination of a stable effective permeability of 26.2 up to 1 MHz, a total core loss of 883 kW m⁻³ (100 kHz, 100 mT), and a DC-Bias performance of 79.3% under 100 Oe field, which is even comparable to those of the most prominent SMCs reported so far. These results are meaningful for potentially stimulating the development and application of new low-loss SMCs.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 11","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142412378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis and optical properties of high-quality ultrathin homogeneous GaAs1−xSbx nanowires","authors":"Ran Zhuo,&nbsp;Lianjun Wen,&nbsp;Jian Wang,&nbsp;Xiuming Dou,&nbsp;Lei Liu,&nbsp;Xiyu Hou,&nbsp;Dunyuan Liao,&nbsp;Baoquan Sun,&nbsp;Dong Pan,&nbsp;Jianhua Zhao","doi":"10.1007/s11433-024-2467-9","DOIUrl":"10.1007/s11433-024-2467-9","url":null,"abstract":"<div><p>Ternary GaAs_1−<i>x</i>Sb_<i>x</i> nanowires with designable bandgaps and lattice constants show important potential applications in band structure engineering as well as optical and optoelectronic devices. However, large diameters, low aspect ratios and even spontaneous core-shell structures are always found in GaAs_1−<i>x</i>Sb_<i>x</i> nanowires, which are hindering their optical and optoelectronic applications. Here, we report the controlled synthesis of ultrathin GaAs_1−<i>x</i>Sb_<i>x</i> nanowires on Si (111) substrates by molecular-beam epitaxy. It is found that ultrathin GaAs_1−<i>x</i>Sb_<i>x</i> nanowires with a diameter less than 40 nm and an aspect ratio exceeding 35 can be obtained by precisely tuning the Ga flux and the growth temperature. The growth of the ultrathin GaAs_1−<i>x</i>Sb_<i>x</i> nanowires with a large-composition-range (0 ⩽ <i>x</i> ⩽ 0.4) are also achieved by directly tuning the antimony flux. Detailed structural studies confirm that these ultrathin nanowires exhibit high crystal-quality, and no spontaneous core-shell nanostructures are observed along the axial and radial directions of the nanowires. As far as we known, it is the first time that homogeneous GaAs_1−<i>x</i>Sb_<i>x</i> nanowires are grown by molecular-beam epitaxy. Photoluminescence measurements prove that the ultrathin GaAs_1−<i>x</i>Sb_<i>x</i> nanowires have a narrower full width at half maximum of the photoluminescence peak compared with those results reported in the literatures, and their emission wavelengths can be tuned from 850 nm (GaAs) to 1271 nm (GaAs_0.6Sb_0.4). In addition, the optical properties of the ultrathin GaAs_1−<i>x</i>Sb_<i>x</i> nanowires can be further improved by using the Al_0.5Ga_0.5As shell as a passivation layer. Our work lays a foundation for the development of high-performance GaAs_1−<i>x</i>Sb_<i>x</i> nanowire-based optical and optoelectronic devices.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 12","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142264478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Al1−xScxSbyN1−y: An opportunity for ferroelectric semiconductor field effect transistor","authors":"Shujin Guo,&nbsp;Xianghua Kong,&nbsp;Hong Guo","doi":"10.1007/s11433-024-2466-0","DOIUrl":"10.1007/s11433-024-2466-0","url":null,"abstract":"<div><p>For the in-memory computation architecture, a ferroelectric semiconductor field-effect transistor (FeSFET) incorporates ferroelectric material into the FET channel to realize logic and memory in a single device. The emerging group III nitride material Al_1−<i>x</i>Sc_<i>x</i>N provides an excellent platform to explore FeSFET, as this material has significant electric polarization, ferroelectric switching, and high carrier mobility. However, steps need to be taken to reduce the large band gap of ∼5 eV of Al_1−<i>x</i>Sc_<i>x</i>N to improve its transport property for in-memory logic applications. By state-of-the-art first principles analysis, here we predict that alloying a relatively small amount (less than ∼5%) of Sb impurities into Al_1−<i>x</i>Sc_<i>x</i>N very effectively reduces the band gap while maintaining excellent ferroelectricity. We show that the co-doped Sb and Sc act cooperatively to give a significant band bowing leading to a small band gap of ∼1.76 eV and a large polarization parameter ∼0.87 C/m², in the quaternary Al_1−<i>x</i>Sc_<i>x</i>Sb_<i>y</i>N_1−<i>y</i> compounds. The Sb impurity states become more continuous as a result of interactions with Sc and can be used for impurity-mediated transport. Based on the Landau-Khalatnikov model, the Landau parameters and the corresponding ferroelectric hysteresis loops are obtained for the quaternary compounds. These findings indicate that Al_1−<i>x</i>Sc_<i>x</i>Sb_<i>y</i>N_1−<i>y</i> is an excellent candidate as the channel material of FeSFET.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 11","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11433-024-2466-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142264477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High temperature superconductor Na2B2H stabilized by hydrogen intercalation under ambient pressure","authors":"Wendi Zhao,&nbsp;Defang Duan,&nbsp;Zhengtao Liu,&nbsp;Zihao Huo,&nbsp;Shumin Guo,&nbsp;Decheng An,&nbsp;Maosheng Miao,&nbsp;Tian Cui","doi":"10.1007/s11433-024-2447-0","DOIUrl":"10.1007/s11433-024-2447-0","url":null,"abstract":"<div><p>Hydrogenated metal borides have attracted much attention due to their potential high-temperature superconductivity. Here, we propose a new strategy for hydrogen intercalation tuning the stability and superconductivity of the boron honeycomb sublattice, and predict an unprecedented layered compound Na₂B₂H, which hosts excellent superconductivity. Strikingly, the superconducting transition temperature (<i>T</i>_c) of Na₂B₂H reaches 42 K at ambient pressure. The <i>T</i>_c value can be further increase to 63 K under 5% biaxial tensile strain. The excellent superconductivity originates from the strong electron-phonon coupling between the <i>σ</i>-bonding bands near the Fermi level and the B-B stretching optical <i>E′</i> modes. The interstitial electron localization and crystal orbitals of the H-intercalated Na ion layer well match the boron honeycomb lattice and act as a chemical template to stabilize the B layer. Furthermore, the introduction of hydrogen tuned the Fermi level, and the coupling vibration of Na and H ions effectively enhanced the dynamic stability of the structure. Na₂B₂H represents a new family of layered high-temperature superconductors, and the strategy of stabilizing the honeycomb boron sublattice via chemical template hosts great potential for application to more layered compounds.</p></div>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 11","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142411870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unveiling the early universe: Axion-like particles and their role in primordial structure formation","authors":"Sergey G. Rubin","doi":"10.1007/s11433-024-2472-0","DOIUrl":"10.1007/s11433-024-2472-0","url":null,"abstract":"","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":"67 11","pages":""},"PeriodicalIF":6.4,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142411871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}