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Braiding Majorana zero modes is essential for fault-tolerant topological quantum computing. Iron-based superconductors with nontrivial band topology have recently emerged as a surprisingly promising platform for creating distinct Majorana zero modes in magnetic vortices in a single material and at relatively high temperatures. The magnetic field-induced Abrikosov vortex lattice makes it difficult to braid a set of Majorana zero modes or to study the coupling of a Majorana doublet due to overlapping wave functions. Here we report the observation of the proposed quantum anomalous vortex with integer quantized vortex core states and the Majorana zero mode induced by magnetic Fe adatoms deposited on the surface. We observe its hybridization with a nearby field-induced Majorana vortex in iron-based superconductor FeTe 0.55 Se 0.45 . We also observe vortex-free Yu-Shiba-Rusinov bound states at the Fe adatoms with a weaker coupling to the substrate, and discover a reversible transition between Yu-Shiba-Rusinov states and Majorana zero mode by manipulating the exchange coupling strength. The dual origin of the Majorana zero modes, from magnetic adatoms and external magnetic field, provides a new single-material platform for studying their interactions and braiding in superconductors bearing topological band structures. Braiding Majorana modes is essential for topological quantum computing, but it remains difficult to find a suitable platform. Here, the authors report the evidence of hybridization between field-induced and magnetic adatom induced Majorana modes in an iron-based superconductor FeTe 0.55 Se 0.45 , providing a possible single-material platform for braiding Majorana modes.

Through an examination of the case of the iPhone X, this paper demonstrates that Chinese companies involved in the production of the iPhone X have moved up along the global value chain. According to the bill of materials, those companies contributed 25.4% of the value added of the iPhone X. About 45% of the value added of the iPhone X originated in Japan, South Korea, and other economies. The iPhone trade remains a significant element of the statistical distortion of the China–US bilateral trade imbalance. In terms of gross value, the import of one iPhone X results in a USD332.75 trade deficit for the US; measured in terms of the value added, however the deficit is a mere USD104. The depreciation of the Chinese yuan (CNY) has very limited power to counterbalance the tariffs imposed by the Trump administration because the foreign value added embedded in Chinese exports is 33.9% on average. Simulation results show that to counterbalance a 25% tariff, the CNY would have to depreciate by 43.3% against the US dollar on average, and to fully compensate for a 25% tariff burden on the iPhone X, a 400% depreciation of the CNY would be necessary. Hedging the risk of the punitive U.S. tariffs by depreciating the CNY is impossible.

The kagome lattice Co 3 Sn 2 S 2 exhibits the quintessential topological phenomena of a magnetic Weyl semimetal such as the chiral anomaly and Fermi-arc surface states. Probing its magnetic properties is crucial for understanding this correlated topological state. Here, using spin-polarized scanning tunneling microscopy/spectroscopy (STM/S) and non-contact atomic force microscopy (nc-AFM) combined with first-principle calculations, we report the discovery of localized spin-orbit polarons (SOPs) with three-fold rotation symmetry nucleated around single S-vacancies in Co 3 Sn 2 S 2. The SOPs carry a magnetic moment and a large diamagnetic orbital magnetization of a possible topological origin associated relating to the diamagnetic circulating current around the S-vacancy. Appreciable magneto-elastic coupling of the SOP is detected by nc-AFM and STM. Our findings suggest that the SOPs can enhance magnetism and more robust time-reversal-symmetry-breaking topological phenomena. Controlled engineering of the SOPs may pave the way toward practical applications in functional quantum devices. Kagome lattice material Co 3 Sn 2 S 2 is identified as a magnetic Weyl semimetal and its magnetic properties are less studied. Here, the authors observe localized spin-orbit polarons nucleated around single S-vacancies carrying a large diamagnetic orbital magnetism in Co 3 Sn 2 S 2 .

Vortices in topological superconductors may host Majorana zero modes (MZMs), which have been proposed as the building blocks of fault-tolerant topological quantum computers. Recently, a new single-material platform with the potential for realizing MZMs has been discovered in iron-based superconductors, without involving hybrid semiconductor–superconductor structures. Here, we report a detailed scanning tunnelling spectroscopy study of a FeTe0.55Se0.45 single crystal and show that this material hosts two distinct classes of vortex. These differ by a half-integer level shift in the energy spectra of the vortex bound states. This level shift is directly tied to the presence or absence of a zero-bias conductance peak and also alters the ratios of higher energy levels from integer to half-odd-integer. Our model calculations fully reproduce the spectra of these two types of vortex bound state, suggesting the presence of regions with and without topological surface states, which coexist within the same crystal. Our findings provide strong evidence for the presence of MZMs in FeTe0.55Se0.45 and establish it as an excellent platform for further studies.The authors use STM to show that there are two different classes of zero-bias peak in vortex cores of Fe(Te,Se). One class is topological, one not. These are distinguished by a shift in the energy levels of the excited states.

Majorana zero modes (MZMs) are spatially localized, zero-energy fractional quasiparticles with non-Abelian braiding statistics that hold promise for topological quantum computing. Owing to the particle-antiparticle equivalence, MZMs exhibit quantized conductance at low temperature. By using variable-tunnel–coupled scanning tunneling spectroscopy, we studied tunneling conductance of vortex bound states on FeTe0.55Se0.45 superconductors. We report observations of conductance plateaus as a function of tunnel coupling for zero-energy vortex bound states with values close to or even reaching the 2e²/h quantum conductance (where e is the electron charge and h is Planck’s constant). By contrast, no plateaus were observed on either finite energy vortex bound states or in the continuum of electronic states outside the superconducting gap. This behavior of the zero-mode conductance supports the existence of MZMs in FeTe0.55Se0.45.

The control of the Kondo effect is of great interest in single-molecule junction due to its potential applications in spin based electronics. Here, we demonstrate that the Kondo effect is reversibly switched on and off in an iron phthalocyanine (FePc) single-molecule junction by using a superconducting Nb tip. In a scanning tunneling microscope-based Nb-insulator-FePc-Au junction, we achieve a reversible switching between the Kondo dip and inelastic electronic tunneling spectra by simply adjusting the tip-sample distance to tune the tunnel coupling at low temperature. Further approaching the tip leads to the picking up of the molecule to the tip apex, which transfers the geometry of the single-molecule junction into a Nb-FePc-insulator-Au type. As the molecule forms an effective magnetic impurity embedded into the superconducting ground states of the Nb tip, the out-gap Kondo dip switched to an in-gap Yu-Shiba-Rusinov state. Our results open up a new route for manipulating the Kondo effect within a single-molecule junction.

Kagome-lattice materials possess attractive properties for quantum computing applications, but their synthesis remains challenging. Herein, based on the compelling identification of the two cleavable surfaces of Co 3 Sn 2 S 2 , we show surface kagome electronic states (SKESs) on a Sn-terminated triangular Co 3 Sn 2 S 2 surface. Such SKESs are imprinted by vertical p-d electronic hybridization between the surface Sn (subsurface S) atoms and the buried Co kagome-lattice network in the Co 3 Sn layer under the surface. Owing to the subsequent lateral hybridization of the Sn and S atoms in a corner-sharing manner, the kagome symmetry and topological electronic properties of the Co 3 Sn layer is proximate to the Sn surface. The SKESs and both hybridizations were verified via qPlus non-contact atomic force microscopy (nc-AFM) and density functional theory calculations. The construction of SKESs with tunable properties can be achieved by the atomic substitution of surface Sn (subsurface S) with other group III-V elements (Se or Te), which was demonstrated theoretically. This work exhibits the powerful capacity of nc-AFM in characterizing localized topological states and reveals the strategy for synthesis of large-area transition-metal-based kagome-lattice materials using conventional surface deposition techniques. Kagome materials host 2D planes which give rise to kagome physics, but these are typically embedded in the bulk. Huang et al. demonstrate a strategy for generating surface kagome electronic states by vertical p-d electronic hybridization between surface atoms and the buried Co kagome network in Co 3 Sn 2 S 2 .

Atomically precise defect engineering is essential to manipulate the properties of emerging topological quantum materials for practical quantum applications. However, this remains challenging due to the obstacles in modifying the typically complex crystal lattice with atomic precision. Here, we report the atomically precise engineering of the vacancy-localized spin–orbit polarons in a kagome magnetic Weyl semimetal Co 3 Sn 2 S 2 , using scanning tunneling microscope. We achieve the step-by-step repair of the selected vacancies, leading to the formation of artificial sulfur vacancies with elaborate geometry. We find that that the bound states localized around these vacancies undergo a symmetry dependent energy shift towards Fermi level with increasing vacancy size. As the vacancy size increases, the localized magnetic moments of spin–orbit polarons become tunable and eventually become itinerantly negative due to spin–orbit coupling in the kagome flat band. These findings provide a platform for engineering atomic quantum states in topological quantum materials at the atomic scale. Defect engineering in topological materials is a frontier that promises tunable physical properties with rich applications. Here, the authors demonstrate the atomically precise engineering of vacancies in a topological semimetal, which locally tunes the magnetic properties.

In the present study, we explored the anti-tumor and anti-angiogenesis effects of chrysophanol, and to investigate the underlying mechanism of the chrysophanol on anti-tumor and anti-angiogenesis in human lung cancer. The viability of cells was measured by CCK-8 assay, cell apoptosis was measured by Annexin-FITC/PI staining assay, and the cell migration and invasion were analyzed by wound-healing assay and transwell assay. ROS generation and mitochondrial membrane potential were analyzed by DCFH-DA probe and mitochondrial staining kit. Angiogenesis was analyzed by tube formation assay. The expression of CD31 was analyzed by immunofluorescence. The levels of proteins were measured by western blot assay. The anti-tumor effects of chrysophanol in vivo were detected by established xenograft mice model. In this study, we found that the cell proliferation, migration, invasion, tube formation, the mitochondrial membrane potential, and the expression of CD31 were inhibited by chrysophanol in a dose-dependent manner, but cell apoptotic ratios and ROS levels were increased by chrysophanol in a dose-dependent manner. Furthermore, the effects of chrysophanol on A549, H738, and HUVEC cell apoptotic rates were reversed by the ROS inhibitor NAC. Besides, the effects of chrysophanol on HUVEC cell tube formation were reversed by the HIF-1α inhibitor KC7F2 and the VEGF inhibitor axitinib in vitro. Moreover, tumor growth was reduced by chrysophanol, and the expression of CD31, CD34, and angiogenin was suppressed by chrysophanol in vivo. Our finding demonstrated that chrysophanol is a highly effective and low-toxic drug for inhibition of tumor growth especially in high vascularized lung cancer.

Postharvest Hupingzao jujubes are prone to softening and reddening during storage. To investigate the influence of glycine betaine on the fruit quality of cold-stored jujubes, the jujubes were immersed in a 15 mmol L−1 glycine betaine solution for 10 min, then stored at 0 ± 1 °C for 100 days. The relevant physical and chemical quality indicators were determined every 20 days. The results indicated that glycine betaine treatment effectively maintained fruit firmness, reduced weight loss, slowed down the respiration rate, and lessened the redness of the fruit peel. Compared with the control group, the malondialdehyde and H2O2 contents in glycine betaine-treated fruit decreased by 26.65% and 9.04%, respectively. In addition, glycine betaine treatment elevated the contents of non-enzymatic antioxidants, including ascorbic acid, total flavonoids, total phenols, and proanthocyanidins. Meanwhile, the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase in the jujube fruit were enhanced after glycine betaine treatment. In conclusion, glycine betaine treatment preserved the quality of the jujube fruits by enhancing the antioxidant metabolism. The results establish a scientific basis for the potential application of glycine betaine in postharvest fruit preservation, providing a strategy to mitigate storage-related quality deterioration.