SECUF Enables Observation of Fractionalized Superconducting Quantum Magnetic Flux Vortices and Skyrmions

Recently, CAS Member Ding Hong’s team at the Tsung-Dao Lee Institute, Shanghai Jiao Tong University, in collaboration with partners, observed for the first time the fractionalization of quantum magnetic flux vortices and the formation of skyrmions in the iron-based superconductor KFe₂As₂. This work advances fractional magnetic flux vortices from long-standing theoretical hypotheses and indirect observations to the stage of atomic-scale real-space and spectroscopic characterization. It not only provides direct evidence for the formation of fractional magnetic flux vortices in multi-band superconductors and chiral superconducting skyrmions, but also indicates that the “1×1” K cleavage surface of KFe₂As₂ may form a two-dimensional superconducting state with broken time-reversal symmetry under the effect of surface charge-transfer doping. This superconducting state provides a new experimental platform for simulating fractionalized excitations, linearly bound interactions, topological defect formation, and Klein-tunneling-like phenomena in condensed matter systems. The work was carried out at the Ultra-low Temperature and High Magnetic Field Scanning Tunneling Microscopy Experimental Station of SECUF, and the relevant research results were published in Science.

Source: Synergetic Extreme Condition User Facility (SECUF)

SECUF Facilitates Development of Wide-Temperature-Range Topological Thermometer Based on Ta₂Pd₃Te₅

Recently, Researcher Shen Jie from the Institute of Physics, Chinese Academy of Sciences / Beijing National Laboratory for Condensed Matter Physics, in collaboration with partners, utilized the novel properties of the topological material Ta₂Pd₃Te₅ to successfully develop a resistance thermometer suitable for wide-temperature-range measurement, providing a promising direction for topological materials to move toward practical applications. This thermometer can be called a “topological thermometer.” The topological thermometer demonstrates tremendous potential in wide-temperature-range detection. The related technology has been applied for and granted an invention patent, laying the foundation for subsequent application development. This research was carried out at the C3 Ultra-low Temperature and High Magnetic Field Quantum Transport and Manipulation Experimental Station and the C1 Sub-millikelvin Experimental Station of SECUF. The relevant research results were published in npj Quantum Materials.

Source: Synergetic Extreme Condition User Facility (SECUF)

Peking University Develops High-Sensitivity Acoustic Devices Using Large-Scale Free-Standing Two-Dimensional Material Films

Recently, CAS Member Wang Enge, Professor Liu Kaihui, and Special-term Associate Researcher Liu Chang from the School of Physics, Peking University, in collaboration with partners, developed a pressure-assisted two-step transfer method, successfully fabricating large-scale free-standing reduced graphene oxide films with a suspended diameter of 8 centimeters and a diameter-to-thickness ratio of 10⁶, and achieving pressure sensors and acoustic microphones with ultra-high sensitivity and signal-to-noise ratio. The high-sensitivity acoustic devices based on large-scale free-standing two-dimensional material films break through the performance limits of traditional acoustic devices, providing a brand-new material system and design pathway for high-end audio equipment, intelligent human-machine interaction, and acoustic warning and monitoring systems. The relevant research results were published in Nature Communications.

Source: Interdisciplinary Institute of Light-Elements Quantum Materials (LEQM)

Peking University Achieves Three-Dimensional Atomic Structure Visualization of Multiple Light-Element Compounds

Recently, the research group of Gao Peng from the Electron Microscopy Laboratory, the Interdisciplinary Institute of Light-Elements Quantum Materials (LEQM), and the International Center for Quantum Materials, Peking University, successfully made the three-dimensional atomic configurations of light atoms in multiple light-element materials directly “visible” using the advanced technique of multi-slice electron ptychography. The Electron Microscopy Laboratory of Peking University has made this technique available on its public platform. This technique is expected to be further expanded and widely applied to more functional material systems containing light elements, providing key technical support for atomic-scale precision design of related materials. The relevant results were published in the Journal of the American Chemical Society and Nature Communications.

Source: School of Physics, Peking University

Institute of Mechanics Proposes New Theory of Liquid Viscosity Based on Instantaneous Normal Modes

Recently, the research team from the State Key Laboratory of Nonlinear Mechanics under Extreme Conditions, Institute of Mechanics, Chinese Academy of Sciences, in collaboration with domestic and international partners, addressed the dilemma that liquids lack a normal mode description similar to solids, and that the Green-Kubo formula and Einstein-Stokes relation are difficult to reveal details of atomic motion. Based on the non-affine linear response theory framework, they decomposed liquid viscosity into various instantaneous normal modes, achieving spectral decomposition of viscosity into atomic-level vibrational modes. They established a quantitative connection between liquid viscosity and specific atomic vibrational modes and thereby resolved the long-standing controversy regarding the physical meaning of “unstable localized modes.” This theory not only explains the origin of liquid viscosity but also provides a theoretical pathway based on fundamental excitations for predicting the rheological properties of complex liquids. The relevant research results were published in Acta Materialia.

Source: Institute of Mechanics, Chinese Academy of Sciences

Institute of Mechanics Proposes Arc-Shaped Triboelectric Nanogenerator, Achieving Over 2000-Fold Enhancement in Current Density Under Ultra-Low Excitation

Recently, Researcher Su Yewang’s team from the Institute of Mechanics, Chinese Academy of Sciences, in collaboration with multiple institutions, proposed an arc-shaped triboelectric nanogenerator (A-TENG) design strategy. Through the elastic energy storage and release mechanism of the arc-shaped structure, ultra-low-speed input is converted into high-speed motion of components, achieving an over 2000-fold enhancement in current density. The A-TENG design proposed by the research team can break through the performance bottleneck of traditional triboelectric nanogenerators under ultra-low-speed external excitation. Utilizing A-TENG, self-powered identity recognition applications can be realized based on Morse code, stably outputting electrical signals under both normal-speed and ultra-low-speed pressing. The average accuracy of identity recognition for up to 6 people based on pressing timing features reaches 95.42%, providing a brand-new solution for ultra-low-speed mechanical energy harvesting and self-powered sensing scenarios. The relevant research results were published in Advanced Energy Materials.

Source: Institute of Mechanics, Chinese Academy of Sciences

National Space Science Center Simulates the Impact of Solar Polar Magnetic Fields on Coronal Mass Ejection Propagation

Recently, Researcher Feng Xueshang’s team from the State Key Laboratory of Solar Activity and Space Weather, National Space Science Center, Chinese Academy of Sciences, utilized the self-developed AMR-SIP-CISM solar wind model. Building upon previous research on the December 4, 2021 coronal mass ejection (CME) event observed by satellites such as Tianwen-1, they further systematically simulated the impact of different solar polar magnetic field strengths on CME propagation from the Sun to the vicinity of Mars. By analyzing solar wind structure, CME propagation and expansion processes, and force mechanisms, they found that as the solar polar magnetic field strengthens, CME propagation speed slows down, spatial scale decreases, and arrival times at BEPIC, Orbito, and MAVEN/Tianwen-1 are significantly delayed. This research quantifies the role of solar polar magnetic fields in regulating CMEs (three-layer evolution), laying groundwork for understanding solar space weather processes. The relevant research was published in The Astrophysical Journal.

Source: National Space Science Center, Chinese Academy of Sciences

Grating Near-Field Enhanced Transverse Broadening Enables Ultrafast Electron Microscope Pulse Timing Measurement

Recently, Researcher Yang Huaixin from the Institute of Physics, Chinese Academy of Sciences / Beijing National Laboratory for Condensed Matter Physics, in collaboration with partners, utilized the transverse broadening effect of electron beams caused by the interaction between free electrons and phase-matched grating near-fields, developing a new method for measuring pulse width without requiring an energy filtering system. This method directly obtains the temporal profile of electron pulses through the variation of the electron beam transverse broadening amplitude over time, achieving ultrafast, high-precision measurement of ultrafast electron microscope (UEM) pulsed electron beams and revealing the dominant role of electrostatic lens temporal aberration in pulse asymmetric broadening. This provides a convenient characterization method and a novel perspective for breaking through the existing UEM temporal resolution bottleneck. The research was carried out at the D4 Experimental Station of SECUF, and the relevant research results were published in Review of Scientific Instruments.

Source: Synergetic Extreme Condition User Facility (SECUF)

Institute of Atmospheric Physics Reveals Strong Radiative Warming Effect of Dark Brown Carbon in Global Wildfire Smoke

Recently, Researcher Chen Xi’s team from the Institute of Atmospheric Physics, Chinese Academy of Sciences, in collaboration with partners, systematically revealed for the first time the widespread existence of a long-neglected class of “dark brown carbon” aerosols in global wildfire smoke and their impact on climate warming, which may far exceed previous understanding. The research team comprehensively utilized aircraft observations, ground-based observations, and satellite remote sensing data to conduct a systematic analysis of dark brown carbon in global wildfire smoke. The results show that dark brown carbon has significant light absorption capacity in the visible light band, and its contribution to visible light can reach or even exceed that of black carbon under equivalent conditions. Dark brown carbon is a key yet long-underestimated climate warming factor. This work received technical support from the Earth System Science Numerical Simulator Facility (EarthLab). The relevant research results were published in Nature Geoscience.

Source: Institute of Atmospheric Physics, Chinese Academy of Sciences