Kosterlitz-Thouless melting of magnetic order in the triangular quantum Ising material TmMgGaO4

Frustrated magnets hold the promise of material realizations of exotic phases of quantum matter, but direct comparisons of unbiased model calculations with experimental measurements remain very challenging. Here we design and implement a protocol of employing many-body computation methodologies for accurate model calculations-of both equilibrium and dynamical properties-for a frustrated rare-earth magnet TmMgGaO4 (TMGO), which explains the corresponding experimental findings. Our results confirm TMGO is an ideal realization of triangular-lattice Ising model with an intrinsic transverse field. The magnetic order of TMGO is predicted to melt through two successive Kosterlitz-Thouless (KT) phase transitions, with a floating KT phase in between. The dynamical spectra calculated suggest remnant images of a vanishing magnetic stripe order that represent vortex-antivortex pairs, resembling rotons in a superfluid helium film. TMGO therefore constitutes a rare quantum magnet for realizing KT physics, and we further propose experimental detection of its intriguing properties. TmMgGaO4 is one of a number of recently-synthesized quantum magnets that are proposed to realize important theoretical models. Here the authors demonstrate the agreement between detailed experimental measurements and state-of-the-art predictions based on the 2D transverse-field triangular lattice Ising model

Full velocities and propagation directions of coronal mass ejections inferred from simultaneous full-disk imaging and Sun-as-a-star spectroscopic observations

Coronal mass ejections (CMEs) are violent ejections of magnetized plasma from the Sun, which can trigger geomagnetic storms, endanger satellite operations and destroy electrical infrastructures on the Earth. After systematically searching Sun-as-a-star spectra observed by the Extreme-ultraviolet Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO) from May 2010 to May 2022, we identified eight CMEs associated with flares and filament eruptions by analyzing the blue-wing asymmetry of the O III 52.58 nm line profiles. Combined with images simultaneously taken by the 30.4 nm channel of the Atmospheric Imaging Assembly onboard SDO, the full velocity and propagation direction for each of the eight CMEs are derived. We find a strong correlation between geomagnetic indices (Kp and Dst) and the angle between the CME propagation direction and the Sun-Earth line, suggesting that Sun-as-a-star spectroscopic observations at EUV wavelengths can potentially help to improve the prediction accuracy of the geoeffectiveness of CMEs. Moreover, an analysis of synthesized long-exposure Sun-as-a-star spectra implies that it is possible to detect CMEs from other stars through blue-wing asymmetries or blueshifts of spectral lines.Comment: Accepted by Ap

Xuebijing Protects Rats from Sepsis Challenged with Acinetobacter baumannii

Xuebijing (XBJ) injection is a herbal medicine that has been widely used in the treatment of sepsis in China; however, its role in the development and progression of Acinetobacter baumannii sepsis and the underlying mechanisms remain uninvestigated. In the present study, fifty-four male Wistar rats were randomly assigned to normal-control group, sepsis-control group, and sepsis + XBJ group, each containing three subgroups of different treatment time periods (6, 12, and 24 hrs following injection, resp.). The sepsis model was established by intraperitoneal injection of A. baumannii ATCC 19606. For XBJ treatment, 4 mL/kg XBJ was administrated simultaneously by intravenous injection through caudal vein every 12 hrs. All animals demonstrated ill state, obvious intestinal dysfunction, histopathological lung damages, and overactive inflammatory responses after A. baumannii infection, and these events could be partially reversed by XBJ treatment from the beginning of infection. XBJ induced an increase in the expression of anti-inflammatory mediator annexin A1; however, two proinflammatory cytokines, interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α), were decreased at the each monitored time point. These findings suggested that XBJ via its cytokine-mediated anti-inflammatory effects might have a potential role in preventing the progression of A. baumannii infection to sepsis by early administration

Untangle charge-order dependent bulk states from surface effects in a topological kagome metal ScV6_6Sn6_6

Kagome metals with charge density wave (CDW) order exhibit a broad spectrum of intriguing quantum phenomena. The recent discovery of the novel kagome CDW compound ScV$_6$Sn$_6$ has spurred significant interest. However, understanding the interplay between CDW and the bulk electronic structure has been obscured by a profusion of surface states and terminations in this quantum material. Here, we employ photoemission spectroscopy and potassium dosing to elucidate the complete bulk band structure of ScV$_6$Sn$_6$, revealing multiple van Hove singularities near the Fermi level. We surprisingly discover a robust spin-polarized topological Dirac surface resonance state at the M point within the two-fold van Hove singularities. Assisted by the first-principle calculations, the temperature dependence of the $k_z$- resolved ARPES spectrum provides unequivocal evidence for the proposed $\sqrt{3}$$\times$$\sqrt{3}$$\times3$ charge order over other candidates. Our work not only enhances the understanding of the CDW-dependent bulk and surface states in ScV$_6$Sn$_6$ but also establishes an essential foundation for potential manipulation of the CDW order in kagome materials.Comment: To appear in PR