Acta Academiae Medicinae Sinicae

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	2024 Vol.41 Issue.11,Published 2024-10-08

	GENERAL THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS ATOMIC AND MOLECULAR PHYSICS FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS) CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS

GENERAL

	110301	Generalized Quantum Measurement in Spin-Correlated Hyperon-Antihyperon Decays
		Sihao Wu, Chen Qian, Yang-Guang Yang, and Qun Wang
		The rapid developments of quantum information science (QIS) have opened up new avenues for exploring fundamental physics. Quantum nonlocality, a key aspect for distinguishing quantum information from classical one, has undergone extensive examinations in particles' decays through the violation of Bell-type inequalities. Despite these advancements, a comprehensive framework based on quantum information theory for particle interaction is still lacking. Trying to close this gap, we introduce a generalized quantum measurement description for decay processes of spin-1/2 hyperons. We validate this approach by aligning it with established theoretical calculations and apply it to the joint decay of $\varLambda\bar{\varLambda}$ pairs. We employ quantum simulation to observe the violation of Clauser–Horne–Shimony–Holt inequalities in $\eta_{c}/\chi_{c0} \to \varLambda\bar{\varLambda}$ processes. Our generalized measurement description is adaptable and can be extended to a variety of high energy processes, including decays of vector mesons, $J/\psi,\,\psi(2S)\rightarrow\varLambda\bar{\varLambda}$, in the Beijing Spectrometer III (BESIII) experiment at the Beijing Electron Positron Collider (BEPC). The methodology developed in this study can be applied to quantum correlation and information processing in fundamental interactions.
		2024 Vol. 41 (11): 110301- [Abstract] ( 70 ) [HTML 1KB] [ PDF 1485KB] ( 96 )

THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

	111101	Discontinuities of Banana Integrals in Dispersion Relation Representation
		Xu-Liang Chen, Peng-Fei Yang, and Wei Chen
		We derive the discontinuities of banana integrals using the dispersion relation iteratively, and find a series of identities between the parameterized discontinuities of banana integrals (p-DOBIs). Similar to elliptic integrals, these identities enable the reduction of various p-DOBIs to be a linear combination of some fundamental ones. We present a practical application of p-DOBIs for deriving the Picard–Fuchs operator. Then we establish the expression of generalized dispersion relation, which enables us to obtain the dispersion relation representation of arbitrary banana integrals. Moreover, we propose a hypothesis for generalized dispersion relation and p-DOBIs, which provides a simple way to calculate the discontinuities and transform dispersion relation representation to p-DOBIs.
		2024 Vol. 41 (11): 111101- [Abstract] ( 33 ) [HTML 1KB] [ PDF 519KB] ( 21 )

	111201	Experimental Road to a Charming Family of Tetraquarks$\ldots$ and Beyond
		Feng Zhu, Gerry Bauer, and Kai Yi
		Discovery of the X(3872) meson in 2003 ignited intense interest in exotic (neither $q\bar{q}$ nor $qqq$) hadrons, but a $c\bar{c}$ interpretation of this state was difficult to exclude. An unequivocal exotic was discovered in the $Z_c(3900)^+$ meson—a charged charmonium-like state. A variety of models of exotic structure have been advanced but consensus is elusive. The grand lesson from heavy quarkonia was that heavy quarks bring clarity. Thus, the recently reported triplet of all-charm tetraquark candidates—$X(6600)$, $X(6900)$, and $X(7100)$—decaying to $J/\psi\,J/\psi$ is a great boon, promising important insights. We review some history of exotics, chronicle the road to prospective all-charm tetraquarks, discuss in some detail the divergent modeling of $J/\psi\,J/\psi$ structures, and offer some inferences about them. These states form a Regge trajectory and appear to be a family of radial excitations. A reported, but unexplained, threshold excess could hint at a fourth family member. We close with a brief look at a step beyond: all-bottom tetraquarks.
		2024 Vol. 41 (11): 111201- [Abstract] ( 159 ) [HTML 1KB] [ PDF 2004KB] ( 128 )

ATOMIC AND MOLECULAR PHYSICS

	113201	Controlling Directional Emission of Ions Attached on Surface of Nanoparticles
		Shuai Ben, Jia-Ying Liang, Yu Pei, Xiao-Hong Song, and Wei-Feng Yang
		The interaction between lasers and nanoparticles holds significant theoretical and practical importance. Here, we investigate the near-field enhancement effects on silver nanotriangles and nanodiscs under ultrafast laser pulses, as well as the dynamics of protons and ions attached to the nanoparticle surfaces. By adjusting the size parameters of the nanoparticles, we explore the near-field enhancement effects and proton emission dynamics at different laser wavelengths. The results demonstrate that nanoparticles with varying morphologies substantially impact the proton momentum spectrum. The directional proton emission of nanotriangle structures is more pronounced compared to that of nanodiscs, and this effect can be further enhanced by adjusting the laser wavelength. Additionally, manipulating the thickness of particles also controls the Mie scattering phenomenon of light. Finally, we qualitatively discuss the emission processes of alpha particles and $^{9}$C$^{6+}$ heavy ions. This research has important implications for proton and heavy ion radiotherapy in cancer treatment and targeted drug delivery, while providing theoretical foundations for understanding, characterizing, and controlling experimental studies of nanosystems with significant potential for expanding research into microdynamic behavior in complex nanomaterial superstructures.
		2024 Vol. 41 (11): 113201- [Abstract] ( 41 ) [HTML 1KB] [ PDF 11895KB] ( 71 )

	113701	Long-Lifetime Optical Trapping of a $^{40}$Ca$^{+}$ Ion
		Zheng Chen, Miao Wang, Baolin Zhang, Huaqing Zhang, Zixiao Ma, Ruming Hu, Yao Huang, Kelin Gao, and Hua Guan
		We have experimentally achieved the all-optical trapping of a $^{40}$Ca$^{+}$ ion. An optical dipole trap was established using a high-power, far-detuned, tightly focused laser with a wavelength of 532 nm. The single $^{40}$Ca$^{+}$ ion was trapped without any RF fields and demonstrated a long lifetime of over 3 s. In this experiment, we implemented several measures to improve the optical trapping probability, including focusing the dipole beam waist near the diffraction limit, precisely compensating for stray electric fields, and mitigating electron shelving in metastable states. The optical trapping of a $^{40}$Ca$^{+}$ ion eliminates the influence of micromotion induced by RF fields, potentially paving the way for development of all-optical trapping ion optical clocks.
		2024 Vol. 41 (11): 113701- [Abstract] ( 75 ) [HTML 1KB] [ PDF 1441KB] ( 83 )

	113702	Manipulation of High-Fidelity Sidebands under Large Detuning by Floquet Technology: Application to Multi-Mode Cooling
		Xue-Ying Yang, Zi-Dong Lin, Shu-Ying Mu, Wei Wu, Chun-Wang Wu, Yi Xie, and Ping-Xing Chen
		The Floquet technology, a powerful way to manipulate quantum states, is employed to drive sidebands transition under large detuning. Our results demonstrate that high fidelities over $99\%$ can be achieved through optimizing suitable modulation frequencies under large detuning. We observe high-fidelity transitions within a high bandwidth by utilizing a single modulation frequency and reveal that this capability is due to the emergence of a flat-band structure in the bandwidth range. The key finding of high-fidelity sideband manipulation under large detuning is experimentally confirmed in nuclear magnetic resonance platform. Finally, we propose a new parallel sideband cooling scheme that enables simultaneous cooling of multiple motional modes. This approach improves the cooling rate compared to conventional schemes with fixed laser frequency and power, and eliminates the need for mode-specific addressing. Our Floquet parallel scheme is applicable to any harmonic oscillator system and is not limited by bandwidth in theory.
		2024 Vol. 41 (11): 113702- [Abstract] ( 60 ) [HTML 1KB] [ PDF 2142KB] ( 51 )

FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS)

	114201	Optical Mode Entanglement Generation from an Optomechanical Nanobeam
		Qi-Zhi Cai, Bo-Yu Fan, Yun-Ru Fan, Guang-Wei Deng, You Wang, Hai-Zhi Song, Guang-Can Guo, and Qiang Zhou
		Nano-optomechanical systems, capable of supporting enhanced light-matter interactions, have wide applications in studying quantum entanglement and quantum information processors. Yet, preparing optical telecom-band entanglement within a single optomechanical nanobeam remains blank. We propose and design a triply resonant optomechanical nanobeam to generate steady-state entangled propagating optical modes and present its quantum-enhanced performance for teleportation-based quantum state transfer under realistic conditions. Remarkably, the entanglement quantified by logarithmic negativity can obtain $E_{\scriptscriptstyle{\rm N}}=1$. Furthermore, with structural imperfections induced by realistic fabrication processes considered, the device still shows great robustness. Together with quantum interfaces between mechanical motion and solid-state qubit processors, the proposed device potentially paves the way for versatile nodes in long-distance quantum networks.
		2024 Vol. 41 (11): 114201- [Abstract] ( 71 ) [HTML 1KB] [ PDF 2411KB] ( 109 )

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

	117101	Pressure-Induced Structural Transition and Enhanced Photoelectric Properties of Tm$_{2}$S$_{3}$
		Zhi-Wei Shen, Zhong-Yan Wu, Shao-Jie Wang, He-Chong Wang, Hong-Kai Li, Jing Song, Guo-Ying Gao, Lin Wang, and Yong-Jun Tian
		Rare earth sesquisulfides have drawn growing attention in photoelectric applications because of their excellent electronic and photoelectric properties upon compression. We investigate the structural, electrical, and photoelectric properties of Tm$_{2}$S$_{3}$ under high pressure through electrical impedance, UV-vis absorption, Raman spectroscopy, x-ray diffraction, and photoelectric measurements. It is found that $\delta$-Tm$_{2}$S$_{3}$ transforms into high-pressure $\alpha$-phase around 5 GPa, accompanied by a substantial reduction in atomic distance, bandgap, and resistivity. Consequently, the photocurrent density and responsivity of Tm$_{2}$S$_{3}$ exhibit dramatic increase behavior, achieving five orders of magnitude enhancement in $\alpha$-phase compared with the initial $\delta$-Tm$_{2}$S$_{3}$. Moreover, $\alpha $-phase maintains a high photocurrent responsivity of three orders of magnitude after unloading. This work demonstrates significant enhancement of the photoelectric properties of Tm$_{2}$S$_{3}$ by applying pressure, which paves the way for improving the performance of future photoelectric devices.
		2024 Vol. 41 (11): 117101- [Abstract] ( 58 ) [HTML 1KB] [ PDF 3073KB] ( 27 )

	117102	Electronic Structure Evolution during Martensitic Phase Transition in All-$d$-Metal Heusler Compounds: The Case of Pd$_{2}$MnTi
		Guijiang Li, Gang Wang, and Enke Liu
		Taking Pd$_{2}$MnTi as a representative example, we systematically investigate and theoretically reveal the electronic structure evolution during martensitic phase transition in all-$d$-metal Heusler compounds. The calculation and theoretical analysis suggest that Pd$_{2}$MnTi is not stable in cubic structure and prone to transform to low-symmetric tetragonal structure. By tetragonal deformation, the shrinkage of lattice parameters and the decrease of symmetry promote the electron accumulation between Pd and its first nearest neighboring Ti atom, resulting in the increasing covalent hybridization. The occurrence of pseudogap in density of states of tetragonal Pd$_{2}$MnTi near the Fermi level also verifies the enhancement of covalent bond. Comparatively, the stronger interatomic bond in tetragonal Pd$_{2}$MnTi, i.e., covalent bond here, would strengthen interatomic coupling and consequently lower the energy of the material. By the martensitic phase transition, more stable states in energy are achieved. Thus, based on the analysis of electronic structure evolution, the nature of martensitic phase transition is a process wherein symmetry breaking weakens the original weak chemical bonds in high-symmetric parent phase and induces the strong chemical bond to lower the energy of the materials and to achieve a more stable state. This study could help to deepen the understanding of martensitic phase transition and the exploration of novel materials for potential technical applications.
		2024 Vol. 41 (11): 117102- [Abstract] ( 40 ) [HTML 1KB] [ PDF 2005KB] ( 41 )

	117201	Tunneling Barrier Thickness Dependence of Spin Polarization of Ferromagnet in Magnetic Tunnel Junctions
		Yu-Qing Zhao, Hai-Yan Zuo, Shao-Wei Li, Ke Xia, Ming Wen, Jun-Mei Guo, Peng Xiong, and Cong Ren
		For designing low-impedance magnetic tunnel junctions (MTJs), it has been found that tunneling magnetoresistance strongly correlates with the insulating barrier thickness, imposing a fundamental problem about the relationship between spin polarization of ferromagnet and the insulating barrier thickness in MTJs. Here, we investigate the influence of alumina barrier thickness on tunneling spin polarization (TSP) through a combination of theoretical calculations and experimental verification. Our simulating results reveal a significant impact of barrier thickness on TSP, exhibiting an oscillating decay of TSP with the barrier layer thinning. Experimental verification is realized on FeNi/AlO$_x$/Al superconducting tunnel junctions to directly probe the spin polarization of FeNi ferromagnet using Zeeman-split tunneling spectroscopy technique. These findings provide valuable insights for designs of high-performance spintronic devices, particularly in applications such as magnetic random access memories, where precise control over the insulating barrier layer is crucial.
		2024 Vol. 41 (11): 117201- [Abstract] ( 40 ) [HTML 1KB] [ PDF 2828KB] ( 75 )

	117301	Sr-Doping-Modulated Metal-Insulator Transition in NdNiO$_{3}$ Epitaxial Films
		Huan Ye, Enda Hua, Fang Xu, Jingdi Lu, Feng Jin, Wenbin Wu, Liang, Si, and Lingfei Wang
		Perovskite-structured nickelates, ReNiO$_{3}$ (Re = rare earth), have long garnered significant research interest due to their sharp and highly tunable metal-insulator transitions (MITs). Doping the parent compound ReNiO$_{3}$ with alkaline earth metal can substantially suppress this MIT. Recently, intriguing superconductivity has been discovered in doped infinite-layer nickelates (ReNiO$_{2})$, while the mechanism behind A-site doping-suppressed MIT in the parent compound ReNiO$_{3}$ remains unclear. To address this problem, we grew a series of Nd$_{1-x}$Sr$_{x}$NiO$_{3}$ (NSNO, $x =0$–0.2) thin films and conducted systematic electrical transport measurements. Our resistivity and Hall measurements suggest that Sr-induced excessive holes are not the primary reason for MIT suppression. Instead, first-principles calculations indicate that Sr cations, with larger ionic radius, suppress breathing mode distortions and promote charge transfer between oxygen and Ni cations. This process weakens Ni–O bond disproportionation and Ni$^{2+}$/Ni$^{4+}$ charge disproportionation. Such significant modulations in lattice and electronic structures convert the ground state from a charge-disproportionated antiferromagnetic insulator to a paramagnetic metal, thereby suppressing the MIT. This scenario is further supported by the weakened MIT observed in the tensile-strained NSNO/SrTiO$_3$(001) films. Our work reveals the A-side doping-modulated electrical transport of perovskite nickelate films, providing deeper insights into novel electric phases in these strongly correlated nickelate systems.
		2024 Vol. 41 (11): 117301- [Abstract] ( 104 ) [HTML 1KB] [ PDF 2883KB] ( 132 )

	117401	Observation of Zero-Energy Modes with Possible Time-Reversal Symmetry Breaking on Step Edge of CaKFe$_{4}$As$_{4}$
		Lu Cao, Geng Li, Wenyao Liu, Ya-Bin Liu, Hui Chen, Yuqing Xing, Lingyuan Kong, Fazhi Yang, Quanxin Hu, Meng Li, Xingtai Zhou, Zichao Chen, Chenhang Ke, Lunhui Hu, Guang-Han Cao, Congjun Wu, Hong Ding, and Hong-Jun Gao ^Hot!
		Topologically nontrivial Fe-based superconductors attract extensive attentions due to their ability of hosting Majorana zero modes (MZMs) which could be used for topological quantum computation. Topological defects such as vortex lines are required to generate MZMs. Here, we observe the robust edge states along the surface steps of CaKFe$_{4}$As$_{4}$. Remarkably, the tunneling spectra show a sharp zero-bias peak (ZBP) with multiple integer-quantized states at the step edge under zero magnetic field. We propose that the increasing hole doping around step edges may drive the local superconductivity into a state with possible spontaneous time-reversal symmetry breaking. Consequently, the ZBP can be interpreted as an MZM in an effective vortex in the superconducting topological surface state by proximity to the center of a tri-junction with different superconducting order parameters. Our results provide new insights into the interplay between topology and unconventional superconductivity, and pave a new path to generate MZMs without magnetic field.
		2024 Vol. 41 (11): 117401-117401 [Abstract] ( 228 ) [HTML 1KB] [ PDF 4403KB] ( 263 )

	117402	Review of the Research Status of Practical Superconducting Materials and Their Current Carrying Performance
		Yifan Zhang, Shengnan Zhang, Jixing Liu, Fang Yang, Chengshan Li, Jianfeng Li, and Pingxiang Zhang
		Superconducting materials hold great potential in high field magnetic applications compared to traditional conductive materials. At present, practical superconducting materials include low-temperature superconductors such as NbTi and Nb$_{3}$Sn, high-temperature superconductors such as Bi-2212, Bi-2223, YBCO, iron-based superconductors and MgB$_{2}$. The development of low-temperature superconducting wires started earlier and has now entered the stage of industrialized production, showing obvious advantages in mechanical properties and cost under low temperature and middle-low magnetic field. However, due to the insufficient intrinsic superconducting performance, low-temperature superconductors are unable to exhibit excellent performance at high temperature or high fields. Further improvement of supercurrent carrying performance mainly depends on the enhancement of pinning ability. High-temperature superconductors have greater advantages in high temperature and high field, but many of them are still in the stage of further performance improvement. Many high-temperature superconductors are limited by the deficiency in their polycrystalline structure, and further optimization of intergranular connectivity is required. In addition, it is also necessary to further enhance their pinning ability. The numerous successful application instances of high-temperature superconducting wires and tapes also prove their tremendous potential in electric power applications.
		2024 Vol. 41 (11): 117402- [Abstract] ( 84 ) [HTML 1KB] [ PDF 11157KB] ( 75 )

	117403	High-Temperature Phonon-Mediated Superconductivity with $T_{\rm c}$ above 100 K in Monolayer Na(BC)$_{2}$ and K(BC)$_{2}$
		Wenxuan Chen, Zhengtao Liu, Zihao Huo, Guiyan Dong, Jialiang Cai, and Defang Duan
		Two-dimensional (2D) materials have demonstrated promising prospects owing to their distinctive electronic properties and exceptional mechanical properties. Among them, 2D superconductors with $T_{\rm c}$ above the boiling point of liquid nitrogen (77 K) will exhibit tremendous applicable value in the future. Here, we design two 2D superconductors Na(BC)$_{2}$ and K(BC)$_{2}$ with MgB$_{2}$-like structures, which are theoretically predicted to host $T_{\rm c}$ as high as 99 and 102 K, respectively. The origin of such high $T_{\rm c}$ is ascribed to the presence of both $\sigma$-bonding bands and van Hove singularity at the Fermi level. Furthermore, $T_{\rm c}$ of Na(BC)$_{2}$ is boosted up to 153 K with a biaxial strain of 5%, which sets a new record among 2D superconductors. The predictions of Na(BC)$_{2}$ and K(BC)$_{2}$ open the door to explore 2D high-temperature superconductors and provide a potential future for developing new applications in 2D materials.
		2024 Vol. 41 (11): 117403- [Abstract] ( 48 ) [HTML 1KB] [ PDF 4100KB] ( 103 )

	117404	Two Distinct Charge Orders in Infinite-Layer PrNiO$_{2+\delta}$ Revealed by Resonant X-Ray Diffraction
		Xiaolin Ren, Ronny Sutarto, Qiang Gao, Qisi Wang, Jiarui Li, Yao Wang, Tao Xiang, Jiangping Hu, J. Chang, Riccardo Comin, X. J. Zhou, and Zhihai Zhu ^Hot!
		Research of infinite-layer nickelates has unveiled a broken translation symmetry, which has sparked significant interest in its root, its relationship to superconductivity, and its comparison to charge order in cuprates. In this study, resonant x-ray scattering measurements were performed on thin films of infinite-layer PrNiO$_{2+\delta}$. The results show significant differences in the superlattice reflection at the Ni $L_{3}$ absorption edge compared to that at the Pr $M_{5}$ resonance in their dependence on energy, temperature, and local symmetry. These differences point to two distinct charge orders, although they share the same in-plane wavevectors. It is suggested that these dissimilarities could be linked to the excess oxygen dopants, given that the resonant reflections were observed in an incompletely reduced PrNiO$_{2+\delta}$ film. Furthermore, azimuthal analysis indicates that the oxygen ligands likely play a crucial role in the charge modulation revealed at the Ni $L_{3}$ resonance.
		2024 Vol. 41 (11): 117404-117404 [Abstract] ( 271 ) [HTML 1KB] [ PDF 4061KB] ( 455 )

	117501	Pathfinding Pulsar Observations with the CVN Incorporating the FAST
		Zhen Yan, Zhiqiang Shen, Peng Jiang, Bo Zhang, Haiyan Zhang, Lang Cui, Jintao Luo, Rurong Chen, Wu Jiang, Hua Zhang, De Wu, Rongbing Zhao, Jianping Yuan, Yue Hu, Yajun Wu, Bo Xia, Guanghui Li, Yongnan Rao, Chenyu Chen, Xiaowei Wang, Hao Ding, Yongpeng Liu, Fuchen Zhang, and Yongbin Jiang
		The importance of Very Long Baseline Interferometry (VLBI) for pulsar research is becoming increasingly prominent and receiving more and more attention. We present the pathfinding pulsar observation results with the Chinese VLBI Network (CVN) incorporating the Five-hundred-meter Aperture Spherical radio Telescope (FAST). On MJD 60045 (11th April 2023), PSRs B0919+06 and B1133+16 were observed with the phase-referencing mode in the L-band using four radio telescopes (FAST, TianMa, Haoping, and Nanshan) and correlated with the pulsar binning mode of the distributed FX-style software correlator in Shanghai. After further data processing with the NRAO Astronomical Image Processing System (AIPS), we detected these two pulsars and fitted their current positions with accuracy at the milliarcsecond level. By comparison, our results show significantly better agreement with predicted values based on historical VLBI observations than those with previous timing observations, as pulsar astrometry with the VLBI provides a more direct and model-independent method for accurately obtaining related parameters.
		2024 Vol. 41 (11): 117501- [Abstract] ( 698 ) [HTML 1KB] [ PDF 876KB] ( 94 )

	117502	Microscopic Theory of Nonlinear Hall Effect in Three-Dimensional Magnetic Systems
		Wen-Tao Hou and Jiadong Zang
		Nonlinear Hall effect (NLHE) has been detected in various of condensed matter systems. Unlike linear Hall effect, NLHE may exist in physical systems with broken inversion symmetry in crystals. On the other hand, real space spin texture may also break inversion symmetry and result in NLHE. We employ the Feynman diagrammatic technique to calculate non-linear Hall conductivity (NLHC) in three-dimensional magnetic systems. The results connect NLHE with the physical quantity of emergent electrodynamics which originates from the magnetic texture. The leading order contribution of NLHC, $\chi_{abb}$, is proportional to the emergent toroidal moment $\mathcal{T}_{a}^{\rm e}$, which reflects how the spin textures wind in three dimensions.
		2024 Vol. 41 (11): 117502- [Abstract] ( 38 ) [HTML 1KB] [ PDF 876KB] ( 22 )

	117503	Spin Dynamics and Phonons in Chromites CoCr$_{2}$O$_{4}$ and MnCr$_{2}$O$_{4}$
		Wei Xu, Gaoting Lin, Mingfang Shu, Jinlong Jiao, Jinfeng Zhu, Qingyong Ren, Manh Duc Le, Xuan Luo, Yuping Sun, Yi Liu, Zhe Qu, Haidong Zhou, Shang Gao, and Jie Ma
		Spinel compounds are of great interest in both fundamental and application-oriented perspectives due to the geometric magnetic frustration inherent to their lattice and the resulting complex magnetic states. Here, we applied x-ray diffraction, magnetization, heat capacity and powder inelastic neutron scattering measurements, along with theoretical calculations, to study the exotic properties of chromite-spinel oxides CoCr$_{2}$O$_{4}$ and MnCr$_{2}$O$_{4}$. The temperature dependence of the phonon spectra provides an insight into the correlation between oxygen motion and the magnetic order, as well as the magnetoelectric effect in the ground state of MnCr$_{2}$O$_{4}$. Moreover, spin-wave excitations in CoCr$_{2}$O$_{4}$ and MnCr$_{2}$O$_{4}$ are compared with Heisenberg model calculations. This approach enables the precise determination of exchange energies and offers a comprehensive understanding of the spin dynamics and relevant exchange interactions in complicated spiral spin ordering.
		2024 Vol. 41 (11): 117503- [Abstract] ( 49 ) [HTML 1KB] [ PDF 2386KB] ( 49 )

	117504	Fermionized Dual Vortex Theory for Magnetized Kagomé Spin Liquid
		Si-Yu Pan and Gang v. Chen
		Inspired by the recent quantum oscillation measurement on the kagomé lattice antiferromagnet in finite magnetic fields, we raise the question about the physical contents of the emergent fermions and the gauge fields if the $U(1)$ spin liquid is relevant for the finite-field kagomé lattice antiferromagnet. Clearly, the magnetic field is non-perturbative in this regime, and the finite-field state has no direct relation with the $U(1)$ Dirac spin liquid proposal at zero field. We here consider the fermionized dual vortex liquid state as one possible candidate theory to understand the magnetized kagomé spin liquid. Within the dual vortex theory, the $S^z$ magnetization is the emergent $U(1)$ gauge flux, and the fermionized dual vortex is the emergent fermion. The magnetic field polarizes the spin component that modulates the $U(1)$ gauge flux for the fermionized vortices and generates the quantum oscillation. Within the mean-field theory, we discuss the gauge field correlation, the vortex–antivortex continuum and the vortex thermal Hall effect.
		2024 Vol. 41 (11): 117504- [Abstract] ( 38 ) [HTML 1KB] [ PDF 1096KB] ( 36 )

	117505	Rare-Earth Chalcogenides: An Inspiring Playground for Exploring Frustrated Magnetism
		Mingtai Xie, Weizhen Zhuo, Yanzhen Cai, Zheng Zhang, and Qingming Zhang
		The rare-earth chalcogenide $ARECh_{2}$ family ($A$ = alkali metal or monovalent ions, $RE$ = rare earth, $Ch$ = chalcogen) has emerged as a paradigmatic platform for studying frustrated magnetism on a triangular lattice. The family members exhibit a variety of ground states, from quantum spin liquid to exotic ordered phases, providing fascinating insight into quantum magnetism. Their simple crystal structure and chemical tunability enable systematic exploration of competing interactions in quantum magnets. Recent neutron scattering and thermodynamic studies have revealed rich phase diagrams and unusual excitations, refining theoretical models of frustrated systems. This review provides a succinct introduction to $ARECh_{2}$ research. It summarizes key findings on crystal structures, single-ion physics, magnetic Hamiltonians, ground states, and low-energy excitations. By highlighting current developments and open questions, we aim to catalyze further exploration and deeper physical understanding on this frontier of quantum magnetism.
		2024 Vol. 41 (11): 117505- [Abstract] ( 81 ) [HTML 1KB] [ PDF 2829KB] ( 83 )

	117701	Effects of Thickness and Anisotropic Strain on Polarization Switching Properties of Sub-10 nm Epitaxial Hf$_{0.5}$Zr$_{0.5}$O$_{2}$ Thin Films
		Kuan Liu, Kai Liu, Xingchang Zhang, Jie Fang, Feng Jin, Wenbin Wu, Chao Ma, and Lingfei Wang
		Doped HfO$_{2}$-based ferroelectric (FE) films are emerging as leading contenders for next-generation FE non-volatile memories due to their excellent compatibility with complementary metal oxide semiconductor processes and robust ferroelectricity at nanoscale dimensions. Despite the considerable attention paid to the FE properties of HfO$_{2}$-based films in recent years, enhancing their polarization switching speed remains a critical research challenge. We demonstrate the strong ferroelectricity of sub-10 nm Hf$_{0.5}$Zr$_{0.5}$O$_{2}$ (HZO) thin films and show that the polarization switching speed of these thin films can be significantly affected by HZO thickness and anisotropically strained La$_{0.67}$Sr$_{0.33}$MO$_{3}$-buffered layer. Our observations indicate that the HZO thin film thickness and anisotropically strained La$_{0.67}$Sr$_{0.33}$MO$_{3}$ layer influence the nucleation of reverse domains by altering the phase composition of the HZO thin film, thereby reducing the polarization switching time. Although the increase in HZO thickness and anisotropic compressive strain hinder the formation of the FE phase, they can enable faster switching. Our findings suggest that FE HZO ultrathin films with polar orthorhombic structures have broad application prospects in microelectronic devices. These insights into novel methods for increasing polarization switching speed are poised to advance the development of high-performance FE devices.
		2024 Vol. 41 (11): 117701- [Abstract] ( 101 ) [HTML 1KB] [ PDF 2706KB] ( 86 )

GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS

	119701	Observations of Fast Radio Variations in Microquasars by FAST
		Wei Wang
		Microquasars are the compact objects generally including accreting black holes which produce relativistic jets. The physical mechanisms of jet launching, collimation, and acceleration are poorly understood. Microquasars show strong variability in multi-wavelength observations. In x-rays, the sources show the fast variation features down to millisecond time scales, with the prominent quasiperiodic oscillations (QPOs) around 0.1 Hz–tens of Hz in light curves, however, physical origin of QPOs is still uncertain. FAST as the largest radio telescope provides the opportunity to study fast variability of both radio flux and polarization in microquasars. In the FAST observations from 2020–2022, we reported the first evidence of radio subsecond quasi-periodic oscillations of GRS 1915+105, providing the direct link between QPOs and the dynamics of relativistic jets. These QPOs with the centroid frequency around 5 Hz are transient, accompanied with strong evolution of the spectral index. Combined with multiwavelength observations, we discuss the possible physical models to produce radio QPOs in BH systems: the helical motion of jet knots or precession of the jet base. In near future, high time resolution radio monitoring of microquasars based on FAST is expected to discover more new phenomena in black hole systems, which will be important for understanding the physics in strong gravity.
		2024 Vol. 41 (11): 119701- [Abstract] ( 54 ) [HTML 1KB] [ PDF 4829KB] ( 41 )

	119801	Statistical Properties and Cosmological Applications of Fast Radio Bursts
		Qin Wu and Fa-Yin Wang
		Fast radio burst (FRB) is a type of extragalactic radio signal characterized by millisecond duration, extremely high brightness temperature, and large dispersion measure. It remains a mystery in the universe. Advancements in instrumentation have led to the discovery of 816 FRB sources and 7622 bursts from 67 repeating FRBs (https://blinkverse.alkaidos.cn/). This field is undergoing rapid development, rapidly advancing our understanding of the physics of FRBs as new observational data accumulates. The accumulation of data has also promoted exploration of our universe. In this review, we summarize the statistical analysis and cosmological applications using large samples of FRBs, including the energy functions, the waiting time distributions of repeating FRBs, probe of missing baryons and circumgalactic medium in the universe, measurements of cosmological parameters, exploration of the epoch of re-ionization history, and research of the gravitational lensing of FRBs.
		2024 Vol. 41 (11): 119801- [Abstract] ( 57 ) [HTML 1KB] [ PDF 2256KB] ( 46 )

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