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A new type of fermion, corresponding to a three-fold degeneracy in the electronic band structure of crystalline molybdenum phosphide, is observed, which lies conceptually between Dirac and Weyl fermions. Triple-point fermions Quantum field theory predicts three types of fermion—Dirac, Weyl and Majorana—but so far only the first type has been detected experimentally as an elementary particle in high-energy physics. However, in recent years quasiparticle analogues of all three types have been observed in crystalline materials with non-trivial topological energy structure. These topological systems could potentially also host new types of fermionic quasiparticle that go beyond the standard description from quantum field theory. Hong Ding and colleagues use spectroscopic measurements to study the electronic band structure of the topological semimetal molybdenum phosphide and observe 'triple points'—states with three-fold degeneracy. These states lie conceptually between Dirac points (four-fold degeneracy) and Weyl points (two-fold degeneracy) and are associated with a new type of three-component fermionic quasiparticle. The authors also observe Weyl points in the system, which suggests that it could be used to study the interplay between different types of fermion. In quantum field theory, Lorentz invariance leads to three types of fermion—Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 . The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally 13 , 14 , 15 , 16 , 17 , 18 , and that of Majorana fermions is supported by various experiments 19 , 20 . However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 . Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac–Weyl–Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.

Thermalization is a ubiquitous process of statistical physics, in which a physical system reaches an equilibrium state that is defined by a few global properties such as temperature. Even in isolated quantum many-body systems, limited to reversible dynamics, thermalization typically prevails 1 . However, in these systems, there is another possibility: many-body localization (MBL) can result in preservation of a non-thermal state 2 , 3 . While disorder has long been considered an essential ingredient for this phenomenon, recent theoretical work has suggested that a quantum many-body system with a spatially increasing field—but no disorder—can also exhibit MBL 4 , resulting in ‘Stark MBL’ 5 . Here we realize Stark MBL in a trapped-ion quantum simulator and demonstrate its key properties: halting of thermalization and slow propagation of correlations. Tailoring the interactions between ionic spins in an effective field gradient, we directly observe their microscopic equilibration for a variety of initial states, and we apply single-site control to measure correlations between separate regions of the spin chain. Furthermore, by engineering a varying gradient, we create a disorder-free system with coexisting long-lived thermalized and non-thermal regions. The results demonstrate the unexpected generality of MBL, with implications about the fundamental requirements for thermalization and with potential uses in engineering long-lived non-equilibrium quantum matter. Experiments with a trapped-ion quantum simulator observe Stark many-body localization, in which the quantum system evades thermalization despite having no disorder.

The intertwining between spin, charge, and lattice degrees of freedom can give rise to unusual macroscopic quantum states, including high-temperature superconductivity and quantum anomalous Hall effects. Recently, a charge density wave (CDW) has been observed in the kagome antiferromagnet FeGe, indicative of possible intertwining physics. An outstanding question is that whether magnetic correlation is fundamental for the spontaneous spatial symmetry breaking orders. Here, utilizing elastic and high-resolution inelastic x-ray scattering, we observe a c-axis superlattice vector that coexists with the 2 × 2 × 1 CDW vectors in the kagome plane. Most interestingly, between the magnetic and CDW transition temperatures, the phonon dynamical structure factor shows a giant phonon-energy hardening and a substantial phonon linewidth broadening near the c-axis wavevectors, both signaling the spin-phonon coupling. By first principles and model calculations, we show that both the static spin polarization and dynamic spin excitations intertwine with the phonon to drive the spatial symmetry breaking in FeGe. The interplay between magnetism and charge density wave in the kagome magnet FeGe is under debate. By using elastic and inelastic X-ray scattering, angle-resolved photoemission spectroscopy, and first principles calculations, Miao et al. propose that the charge density wave is stabilized by spin-phonon coupling.

Cardiac progenitor cells derived from adult heart have emerged as one of the most promising stem cell types for cardiac protection and repair. Exosomes are known to mediate cell–cell communication by transporting cell-derived proteins and nucleic acids, including various microRNAs (miRNAs). Here we investigated the cardiac progenitor cell (CPC)-derived exosomal miRNAs on protecting myocardium under oxidative stress. Sca1 + CPCs-derived exosomes were purified from conditional medium, and identified by nanoparticle trafficking analysis (NTA), transmission electron microscopy and western blotting using CD63, CD9 and Alix as markers. Exosomes production was measured by NTA, the result showed that oxidative stress-induced CPCs secrete more exosomes compared with normal condition. Although six apoptosis-related miRNAs could be detected in two different treatment-derived exosomes, only miR-21 was significantly upregulated in oxidative stress-induced exosomes compared with normal exosomes. The same oxidative stress could cause low miR-21 and high cleaved caspase-3 expression in H9C2 cardiac cells. But the cleaved caspase-3 was significantly decreased when miR-21 was overexpressed by transfecting miR-21 mimic. Furthermore, miR-21 mimic or inhibitor transfection and luciferase activity assay confirmed that programmed cell death 4 (PDCD4) was a target gene of miR-21, and miR-21/PDCD4 axis has an important role in anti-apoptotic effect of H9C2 cell. Western blotting and Annexin V/PI results demonstrated that exosomes pre-treated H9C2 exhibited increased miR-21 whereas decreased PDCD4, and had more resistant potential to the apoptosis induced by the oxidative stress, compared with non-treated cells. These findings revealed that CPC-derived exosomal miR-21 had an inhibiting role in the apoptosis pathway through downregulating PDCD4. Restored miR-21/PDCD4 pathway using CPC-derived exosomes could protect myocardial cells against oxidative stress-related apoptosis. Therefore, exosomes could be used as a new therapeutic vehicle for ischemic cardiac disease.

Crystal defects can confine isolated electronic spins and are promising candidates for solid-state quantum information. Alongside research focusing on nitrogen-vacancy centres in diamond, an alternative strategy seeks to identify new spin systems with an expanded set of technological capabilities, a materials-driven approach that could ultimately lead to ‘designer’ spins with tailored properties. Here we show that the 4H, 6H and 3C polytypes of SiC all host coherent and optically addressable defect spin states, including states in all three with room-temperature quantum coherence. The prevalence of this spin coherence shows that crystal polymorphism can be a degree of freedom for engineering spin qubits. Long spin coherence times allow us to use double electron–electron resonance to measure magnetic dipole interactions between spin ensembles in inequivalent lattice sites of the same crystal. Together with the distinct optical and spin transition energies of such inequivalent states, these interactions provide a route to dipole-coupled networks of separately addressable spins. Silicon carbide is a polymorphic material with over 250 known crystal structures. Here the authors show that such polymorphism can be used as a degree of freedom for engineering optically addressable and coherently interacting spin states, including many with room-temperature quantum coherence.

A state of matter known as a three-dimensional Dirac semimetal has latterly garnered significant theoretical and experimental attention. Using angle-resolved photoelectron spectroscopy, it is shown that Cd 3 As 2 is an experimental realization of a three-dimensional Dirac semimetal that is stable at ambient conditions. Three-dimensional (3D) topological Dirac semimetals (TDSs) are a recently proposed state of quantum matter 1 , 2 , 3 , 4 , 5 , 6 that have attracted increasing attention in physics and materials science. A 3D TDS is not only a bulk analogue of graphene; it also exhibits non-trivial topology in its electronic structure that shares similarities with topological insulators. Moreover, a TDS can potentially be driven into other exotic phases (such as Weyl semimetals 1 , 7 , axion insulators 1 , 4 and topological superconductors 8 , 9 ), making it a unique parent compound for the study of these states and the phase transitions between them. Here, by performing angle-resolved photoemission spectroscopy, we directly observe a pair of 3D Dirac fermions in Cd 3 As 2 , proving that it is a model 3D TDS. Compared with other 3D TDSs, for example, β-cristobalite BiO 2 (ref.  3 ) and Na 3 Bi (refs  4 , 5 ), Cd 3 As 2 is stable and has much higher Fermi velocities. Furthermore, by in situ doping we have been able to tune its Fermi energy, making it a flexible platform for exploring exotic physical phenomena.

At the interface between monolayer FeSe films and SrTiO 3 substrates the superconducting transition temperature ( T c ) is unexpectedly high, triggering a surge of excitement. The mechanism for the T c enhancement has been the central question, as it may present a new strategy for seeking out higher T c materials. To reveal this enigmatic mechanism, by combining advances in high quality interface growth, 16 O ↔ 18 O isotope substitution, and extensive data from angle resolved photoemission spectroscopy, we provide striking evidence that the high T c in FeSe/SrTiO 3 is the cooperative effect of the intrinsic pairing mechanism in the FeSe and interactions between the FeSe electrons and SrTiO 3 phonons. Furthermore, our results point to the promising prospect that similar cooperation between different Cooper pairing channels may be a general framework to understand and design high-temperature superconductors. The mechanism of enhanced superconducting transition temperature ( T c ) at the FeSe/SrTiO 3 interface remains enigmatic. Here, Song and Yu et al. reveal the evidence of cooperation between intrinsic pairing interaction in FeSe and interfacial electron–phonon coupling to enhance the T c at the FeSe/SrTiO 3 interface.

The discovery of two-dimensional (2D) magnetism within atomically thin structures obtained from layered magnetic crystals has opened up a new realm for exploring magnetic heterostructures. This emerging field provides a foundational platform for investigating unique physical properties and exquisite phenomena at the nanometer and molecular/atomic scales. By engineering 2D interfaces using physical methods and selecting interlayer interactions, we can unlock the potential for extraordinary exchange dynamics, which extends to high-performance and high-density magnetic memory applications, as well as future advancements in neuromorphic and quantum computing. This review delves into recent advances in magnetic 2D materials, elucidates the mechanisms behind 2D interfaces, and highlights the development of 2D devices for spintronics and quantum information processing. Particular focus is placed on 2D magnetic heterostructures with topological properties, promising a resilient and low-error information system. Finally, we discuss the trends of 2D heterostructures for future electronics, considering the challenges and opportunities from physics, material synthesis, and technological perspectives.

A bstract Quirks are generic predictions of strongly-coupled dark sectors. For weak-scale masses and a broad range of confining scales in the dark sector, quirks can be discovered only at the energy frontier, but quirk-anti-quirk pairs are produced with unusual signatures at low p T , making them difficult to detect at the large LHC detectors. We determine the prospects for discovering quirks using timing information at FASER, FASER2, and an “ultimate detector” in the far-forward region at the LHC. NLO QCD corrections are incorporated in the simulation of quirk production, which can significantly increase the production rate. To accurately propagate quirk pairs from the ATLAS interaction point to the forward detectors, the ionization energy loss of charged quirks traveling through matter, the radiation of infracolor glueballs and QCD hadrons during quirk pair oscillations, and the annihilation of quirkonium are properly considered. The quirk signal is separated from the large muon background using timing information from scintillator detectors by requiring either two coincident delayed tracks, based on arrival times at the detector, or two coincident slow tracks, based on time differences between hits in the front and back scintillators. We find that simple cuts preserve much of the signal, but reduce the muon background to negligible levels. With the data already collected, FASER can discover quirks in currently unconstrained parameter space. FASER2, running at the Forward Physics Facility during the HL-LHC era, will greatly extend this reach, probing the TeV-scale quirk masses motivated by the gauge hierarchy problem for the broad range of dark-sector confining scales between 100 eV and 100 keV.

Several previous researches had found artery stiffness associated skeletal muscle mass, but not considering muscle strength and physical performance, which also were compositions of sarcopenia. This study aims to reveal the relationship of artery stiffness and sarcopenia using the Asian Working Group for Sarcopenia criteria. Study was performed on 1002 Chinese community dwelling participants aged ≥65 years from November 2016 to March 2017. Body composition, muscle strength, physical performance, and brachial-ankle pulse wave velocity (baPWV) considering as artery stiffness index were measured. In multiple regression analysis, baPWV was associated with handgrip (β=−0.13, P=0.04) and Relative skeletal muscle mass index (ASM/Ht2) (β=−0.02, P<0.01), but not with 4-meter velocity (P=0.21). Multiple logistic regression analysis showed that 1-SD (3.50m/s) increased in baPWV was still associated with a 11% (CI, 4%–20%; P<0.01) higher odds of being sarcopenia. In the gender subgroup analysis, the relationship of baPWV and sarcopenia remain significant in men (OR, 1.23; 95% CI, 1.07–1.42, P<0.01), but not in women (P=0.07). High brachial-ankle pulse wave velocity is associated with sarcopenia in Chinese community-dwelling elderly, with gender differences.