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The simple kagome-lattice band structure possesses Dirac cones, flat band, and saddle point with van Hove singularities in the electronic density of states, facilitating the emergence of various electronic orders. Here we report a titanium-based kagome metal CsTi3Bi5 where titanium atoms form a kagome network, resembling its isostructural compound CsV3Sb5. Thermodynamic properties including the magnetization, resistance, and heat capacity reveal the conventional Fermi liquid behavior in the kagome metal CsTi3Bi5 and no signature of superconducting or charge density wave (CDW) transition anomaly down to 85 mK. Systematic angle-resolved photoemission spectroscopy measurements reveal multiple bands crossing the Fermi level, consistent with the first-principles calculations. The flat band formed by the destructive interference of hopping in the kagome lattice is observed directly. Compared to CsV3Sb5, the van Hove singularities are pushed far away above the Fermi level in CsTi3Bi5, in line with the absence of CDW. Furthermore, the first-principles calculations identify the nontrivial Z2 topological properties for those bands crossing the Fermi level, accompanied by several local band inversions. Our results suppose CsTi3Bi5 as a complementary platform to explore the superconductivity and nontrivial band topology.

Layered ferromagnets with strong magnetic anisotropy energy (MAE) have special applications in nanoscale memory elements in electronic circuits. Here, we report a strain tunability of perpendicular magnetic anisotropy in van der Waals (vdW) ferromagnets VI

An interplay of geometrical frustration and strong quantum fluctuations in a spin-1/2 triangular-lattice antiferromagnet (TAF) can lead to exotic quantum states. Here, we report the neutron-scattering, magnetization, specific heat, and magnetocaloric studies of the recently discovered spin-1/2 TAF Na

We reported a layer-controlled transition from the soft to hard ferromagnetic state in atomically thin CrSiTe3 flakes. Our study paves the way towards exploring and learning much more atomically thin and layered intrinsic ferromagnets.

Pear has an S-RNase-based gametophytic self-incompatibility (SI) system. Nuclear DNA degradation is a typical feature of incompatible pollen tube death, and is among the many physiological functions of vacuoles. However, the specific changes that occur in vacuoles, as well as the associated regulatory mechanism in pear SI, are currently unclear. Although research in tobacco has shown that, decreased activity of diacylglycerol kinase (DGK) results in the morphological change of pollen tube vacuole, whether DGK regulates the pollen tube vacuole of tree plants and whether it occurs in SI response, is currently unclear. We found DGK activity is essential for pear pollen tube growth, and DGK4 regulates pollen tube vacuole morphology following its high expression and deposition at the tip and shank edge of the pollen tube of pear. Specifically, incompatible S-RNase may induce cytoplasmic acidification of the pollen tube by inhibiting V-ATPase V0 dominant a1 subunit gene expression as early as 30 min after treatment, when the pollen tube is still alive. Cytoplasmic acidification induced by incompatible S-RNase resulting in reduced DGK4 abundance and deposition, leading to morphological change of the vacuole and fragmentation of nuclear DNA, which indicates DGK4 is a key factor in pear SI response. This article is protected by copyright. All rights reserved.

The research on van der Waals (vdW) layered ferromagnets have promoted the development of nanoscale spintronics and applications. However, low-temperature ferromagnetic properties of these materials greatly hinder their applications. Here, we report pressure-enhanced ferromagnetic behaviours in layered CrSiTe3 flakes revealed by high-pressure magnetic circular dichroism (MCD) measurement. At ambient pressure, CrSiTe3 undergoes a paramagnetic-to-ferromagnetic phase transition at 32.8 K, with a negligible hysteresis loop, indicating a soft ferromagnetic behaviour. Under 4.6 GPa pressure, the soft ferromagnet changes into hard one, signalled by a rectangular hysteretic loop with remnant magnetization at zero field. Interestingly, with further increasing pressure, the coercive field (H_c) dramatically increases from 0.02 T at 4.6 GPa to 0.17 T at 7.8 GPa, and the Curie temperature (T_c^h: the temperature for closing the hysteresis loop) also increases from ~36 K at 4.6 GPa to ~138 K at 7.8 GPa. The influences of pressure on exchange interactions are further investigated by density functional theory calculations, which reveal that the in-plane nearest-neighbor exchange interaction and magneto-crystalline anisotropy increase simultaneously as pressure increases, leading to increased H_c and T_c^h in experiments. The effective interaction between magnetic couplings and external pressure offers new opportunities for both searching room-temperature layered ferromagnets and designing pressure-sensitive magnetic functional devices.

Spin-orbit coupled honeycomb magnets with the Kitaev interaction have received a lot of attention due to their potential of hosting exotic quantum states including quantum spin liquids. Thus far, the most studied Kitaev systems are 4d/5d-based honeycomb magnets. Recent theoretical studies predicted that 3d-based honeycomb magnets, including Na2Co2TeO6 (NCTO), could also be a potential Kitaev system. Here, we have used a combination of heat capacity, magnetization, electron spin resonance measurements alongside inelastic neutron scattering (INS) to study NCTO's quantum magnetism, and we have found a field-induced spin disordered state in an applied magnetic field range of 7.5 T < B (vertical to b-axis) < 10.5 T. The INS spectra were also simulated to tentatively extract the exchange interactions. As a 3d-magnet with a field-induced disordered state on an effective spin-1/2 honeycomb lattice, NCTO expands the Kitaev model to 3d compounds, promoting further interests on the spin-orbital effect in quantum magnets., 19 pages and 5 figures for main text. 16 pages and 6 figures for Supplemental Material

Shubnikov-de Hass oscillations are directly observed in undoped antiferromagnetic topological insulator MnBi2Te4. With increasing magnetic fields, the oscillation period decreases gradually in the magnetic transition from canted antiferromagnetism to ferromagnetism and then saturates in high magnetic fields, indicating the field-induced evolution of the band structure. From the analysis of the high-field oscillations, a nontrivial Berry phase and a small effective mass are extracted, in agreement with the predicted Weyl semimetal phase in ferromagnetic MnBi2Te4. Furthermore, rotating the magnetization of MnBi2Te4 can lead to a splitting of the high-field oscillations, which suggests the enhanced asymmetry of the Weyl cones in tilted fields. Therefore, the observation of these magnetically tunable quantum oscillations clearly demonstrates the indispensable role of field in tuning the band structure or physical properties of MnBi2Te4., 13 pages, 5 figures

Lorentz-violating type-II Dirac nodal line semimetals (DNLSs), hosting curves of band degeneracy formed by two dispersion branches with the same sign of slope, represent a novel states of matter. While being studied extensively in theory, convincing experimental evidences of type-II DNLSs remain elusive. Recently, Vanadium-based kagome materials have emerged as a fertile ground to study the interplay between lattice symmetry and band topology. In this work, we study the low-energy band structure of double-kagome-layered CsV$_8$Sb$_{12}$ and identify it as a scarce type-II DNLS protected by mirror symmetry. We have observed multiple DNLs consisting of type-II Dirac cones close to or almost at the Fermi level via angle-resolved photoemission spectroscopy (ARPES). First-principle analyses show that spin-orbit coupling only opens a small gap, resulting effectively gapless ARPES spectra, yet generating large spin Berry curvature. These type-II DNLs, together with the interaction between a low-energy van Hove singularity and quasi-1D band as we observed in the same material, suggest CsV$_8$Sb$_{12}$ as an ideal platform for exploring novel transport properties such as chiral anomaly, the Klein tunneling and fractional quantum Hall effect., Comment: 10 pages, 4 figures

Layered ferromagnets with high coercivity have special applications in nanoscale memory elements in electronic circuits, such as data storage. Therefore, searching for new hard ferromagnets and effectively tuning or enhancing the coercivity are the hottest topics in layered magnets today. Here, we report a strain tunability of perpendicular magnetic anisotropy in van der Waals (vdW) ferromagnets VI3 using magnetic circular dichroism measurements. For an unstrained flake, the M-H curve shows a rectangular-shaped hysteresis loop with perpendicular magnetic anisotropy and a large coercivity (up to 1.775 T at 10 K). Furthermore, the coercivity can be enhanced to a maximum of 2.6 T at 10 K under a 2.9% in-plane tensile strain. Our DFT calculations show that the magnetic anisotropy energy (MAE) can be dramatically increased after applying an in-plain tensile strain, which contributes to the enhancement of coercivity in the VI3 flake. Meanwhile, the strain tunability on the coercivity of CrI3, with a similar crystal structure, is limited. The main reason is the strong spin-orbital coupling in V3+ in VI6 octahedra in comparison with that in Cr3+. The strain tunability of coercivity in VI3 flakes highlights its potential for integration into vdW heterostructures, paving the way toward nanoscale spintronic devices and applications in the future.

Arguably the most favorable situation for spins to enter the long-sought quantum spin liquid (QSL) state is when they sit on a kagome lattice. No consensus has been reached in theory regarding the true ground state of this promising platform. The experimental efforts, relying mostly on one archetypal material ZnCu$_3$(OH)$_6$Cl$_2$, have also led to diverse possibilities. Apart from subtle interactions in the Hamiltonian, there is the additional degree of complexity associated with disorder in the real material ZnCu$_3$(OH)$_6$Cl$_2$ that haunts most experimental probes. Here we resort to heat transport measurement, a cleaner probe in which instead of contributing directly, the disorder only impacts the signal from the kagome spins. For ZnCu$_3$(OH)$_6$Cl$_2$ and a related QSL candidate Cu$_3$Zn(OH)$_6$FBr, we observed no contribution by any spin excitation nor any field-induced change to the thermal conductivity. These results impose different constraints on various scenarios about the ground state of these two kagome compounds: while a gapped QSL, or certain quantum paramagnetic state other than a QSL, is compatible with our results, a gapless QSL must be dramatically modified by the disorder so that gapless spin excitations are localized.

We investigated the evolution of ferromagnetism in layered Fe3GeTe2 flakes under different pressures and temperatures using in situ magnetic circular dichroism (MCD) spectroscopy. We found that the rectangular shape of the hysteresis loop under an out-of-plane magnetic field sweep can be sustained below 7 GPa. Above that pressure, an intermediate state appears in the low-temperature region signaled by an 8-shaped skewed hysteresis loop. Meanwhile, the coercive field and Curie temperature decrease with increasing pressures, implying the decrease of the exchange interaction and the magneto-crystalline anisotropy under pressures. The intermediate phase has a labyrinthine domain structure, which is attributed to the increase of the ratio of exchange interaction to magneto-crystalline anisotropy based on Jagla's theory. Moreover, our calculations reveal a weak structural transition around 6 GPa that corresponds to a significant change in the FeI-FeI bond length, which has strong influences on magnetic interaction. Detailed analysis on exchange interaction and magneto-crystalline anisotropy with pressure shows a consistent trend with experiments.

Circularly polarized light carries light spin angular momentum, which may lead helicity-resolved Raman scattering to be sensitive to the electronic spin configuration in magnetic materials. Here, we demonstrate that all Raman modes in the 2D ferromagnet VI3 show different scattering intensities to left and right circularly polarized light at low temperatures, which gives direct evidence of the time-reversal symmetry breaking. By measuring the circular polarization of the dominant Raman mode with respect to the temperature and magnetic field, the ferromagnetic (FM) phase transition and hysteresis behavior can be clearly resolved. Besides the lattice excitations, quasielastic scattering is detected in the paramagnetic phase, and it gradually evolves into the acoustic magnon mode at 18.5 cm-1 in the FM state, which gives the spin wave gap that results from large magnetic anisotropy. Our findings demonstrate that helicity-resolved Raman spectroscopy is an effective tool to directly probe the ferromagnetism in 2D magnets.

We report experimental determination of compressibility and thermoelasticity for CrN based on in situ high pressure/high temperature synchrotron x-ray diffraction measurements. The pressure-induced...

Topological Hall effect is an abnormal Hall response arising from the scalar spin chirality of chiral magnetic textures. Up to now, such an effect is only observed in certain special materials, but rarely in traditional ferromagnets. In this work, we have implemented the molecular beam epitaxy technique to successfully embed black-phosphorus-like bismuth nanosheets with strong spin-orbit coupling into the bulk of chromium telluride Cr2Te3, as evidenced by atomically resolved energy dispersive X-ray spectroscopy mapping. Distinctive from pristine Cr2Te3, these Bi-embedded Cr2Te3 epitaxial films exhibit not only pronounced topological Hall effects, but also magnetoresistivity anomalies and differential magnetic susceptibility plateaus. All these experimental features point to the possible emergence of magnetic skyrmions in Bi-embedded Cr2Te3, which is further supported by our numerical simulations with all input parameters obtained from the first-principle calculations. Therefore, our work demonstrates a new efficient way to induce skyrmions in ferromagnets, as well as the topological Hall effect by embedding nanosheets with strong spin-orbit couplings.

How an interfacial superconductivity emerges during the nucleation and epitaxy is of great importance not only for unveiling the physical insights but also for finding a feasible way to tune the superconductivity via interfacial engineering. In this work, we report the nanoscale creation of a robust and relatively homogeneous interfacial superconductivity (TC ≈ 13 K) on the epitaxial FeTe surface, by van der Waals epitaxy of single-quintuple-layer topological insulator Bi2Te3. Our study suggests that the superconductivity in the Bi2Te3/FeTe heterostructure is generated at the interface and that the superconductivity at the interface does not enhance or weaken with the increase of the Bi2Te3 thickness beyond 1 quintuple layer (QL). The observation of the topological surface states crossing Fermi energy in the Bi2Te3/FeTe heterostructure with the average Bi2Te3 thickness of about 20 QL provides further evidence that this heterostructure may potentially host Majorana zero modes.

The recent discovery of 2D magnets has revealed various intriguing phenomena due to the coupling between spin and other degree of freedoms (such as helical photoluminescence, nonreciprocal SHG). Previous research on the spin-phonon coupling effect mainly focuses on the renormalization of phonon frequency. Here we demonstrate that the Raman polarization selection rules of optical phonons can be greatly modified by the magnetic ordering in 2D magnet CrI$_3$. For monolayer samples, the dominant A$\rm_{1g}$ peak shows abnormally high intensity in the cross polarization channel at low temperature, which is forbidden by the selection rule based on the lattice symmetry. While for bilayer, this peak is absent in the cross polarization channel for the layered antiferromagnetic (AFM) state and reappears when it is tuned to the ferromagnetic (FM) state by an external magnetic field. Our findings shed light on exploring the emergent magneto-optical effects in 2D magnets., Comment: 15 pages, 4 figures

The intertwining of charge order, superconductivity and band topology has promoted the AV$_3$Sb$_5$ (A=K, Rb, Cs) family of materials to the center of attention in condensed matter physics. Underlying those mysterious macroscopic properties such as giant anomalous Hall conductivity (AHC) and chiral charge density wave is their nontrivial band topology. While there have been numerous experimental and theoretical works investigating the nontrivial band structure and especially the van Hove singularities, the exact topological phase of this family remains to be clarified. In this work, we identify CsV$_3$Sb$_5$ as a Dirac nodal line semimetal based on the observation of multiple Dirac nodal lines and loops close to the Fermi level. Combining photoemission spectroscopy and density functional theory, we identify two groups of Dirac nodal lines along $k_z$ direction and one group of Dirac nodal loops in the A-H-L plane. These nodal loops are located at the Fermi level within the instrumental resolution limit. Importantly, our first-principle analyses indicate that these nodal loops may be a crucial source of the mysterious giant AHC observed. Our results not only provide a clear picture to categorize the band structure topology of this family of materials, but also suggest the dominant role of topological nodal loops in shaping their transport behavior.

Despite recent advances in layered ferromagnets, ferromagnetic interactions in these materials are rather weak. Here, we report pressure-enhanced ferromagnetism in layered CrSiTe

The spin-1/2 kagome antiferromagnets are key prototype materials for studying frustrated magnetism. Three isostructural kagome antiferromagnets LnCu$_3$(OH)$_6$Cl$_3$ (Ln = Gd, Tb, Dy) have been successfully synthesized by the hydrothermal method. LnCu$_3$(OH)$_6$Cl$_3$ adopts space group $P\overline{3}m1$ and features the layered Cu-kagome lattice with lanthanide Ln$^{3+}$ cations sitting at the center of the hexagons. Although heavy lanthanides (Ln = Gd, Tb, Dy) in LnCu$_3$(OH)$_6$Cl$_3$ provide a large effective magnetic moment and ferromagnetic-like spin correlations compared to light-lanthanides (Nd, Sm, Eu) analogues, Cu-kagome holds an antiferromagnetically ordered state at around 17 K like YCu$_3$(OH)$_6$Cl$_3$., Accepted by Chinese Physics B

Mermin-Wagner-Coleman theorem predicts no long-range magnetic order at finite temperature in the two-dimensional (2D) isotropic systems, but it does predict a quasi-long-range order with a divergent correlation length at the Kosterlitz-Thouless (KT) transition for planar magnets. As a representative of two-dimensional planar antiferromagnets, single-layer ${\mathrm{CoPS}}_{3}$ carries the promise of monolayer antiferromagnetic platforms for the ultimately thin spintronics. Here, with the aid of magnetostriction which is sensitive to the local magnetic order, we observe the signature phonon mode splitting of below ${T}_{\mathrm{KT}}$ in monolayer ${\mathrm{CoPS}}_{3}$. The two-magnon signal in the monolayer one manifests the associated magnetic transition. It indicates the quasi-long-range order in an exact 2D planar spin model below KT phase transition. The ratio ($J$\ensuremath{'}/$J$) between the interlayer and intralayer interactions, which characterizes the 2D behaviors, is evaluated to be around 0.03. Our results provide an efficient method to detect the quasi-long-range antiferromagnetic ordering in the two-dimensional magnets down to the monolayer limit.

Realization of the quantum anomalous Hall effect and axion electrodynamics in topological materials are among the paradigmatic phenomena in condensed matter physics. Recently, signatures of both phases are observed to exist in thin films of MnBi$_2$Te$_4$, a stoichiometric antiferromagnetic topological insulator. Direct evidence of the bulk topological magnetoelectric response in an axion insulator requires an energy gap at its topological surface state (TSS). However, independent spectroscopic experiments revealed that such a surface gap is absent, or much smaller than previously thought, in MnBi$_2$Te$_4$. Here, we utilize angle resolved photoemission spectroscopy and density functional theory calculations to demonstrate that a sizable TSS gap unexpectedly exists in Sb-doped MnBi$_2$Te$_4$. This gap is found to be topologically nontrivial, insensitive to the bulk antiferromagnetic-paramagnetic transition, while enlarges along with increasing Sb concentration. Our work shows that Mn(Bi$_{1-x}$Sb$_x$)$_2$Te$_4$ is a potential platform to observe the key features of the high-temperature axion insulator state, such as the topological magnetoelectric responses and half-integer quantum Hall effects.

Background Emerging evidence has shown that miR-1275 plays a critical role in tumour metastasis and the progression of various types of cancer. In this study, we analysed the role and mechanism of miR-1275 in the progression and prognosis of gastric cancer (GC). Methods Target genes of miR-1275 were identified and verified by luciferase assay and Western blotting. The function of miR-1275 in invasion and metastasis was analysed in vitro and in vivo in nude mice. The signal pathway regulated by miR-1275 was examined by qRT-PCR, Western blotting and chromatin immunoprecipitation analyses. The expression of miR-1275and JAZF1 were measured in specimens of GC and adjacent non cancerous tissues. Results We identified JAZF1 as a direct miR-1275 target. miR-1275 supresses migration and invasion of GC cells in vitro and in vivo, which was restored by JAZF1 overexpression. Moreover, JAZF1 was recognized as a direct regulator of Vimentin. Knocking-down miR-1275 or overexpressing JAZF1 resulted in upregulation of Vimentin but downregulation of E-cadherin. Meanwhile, we validated in 120 GC patients specimens that low miR-1275expression and high JAZF1 mRNA expression levels were closely associated with lymph node metastasis and poor prognosis. The expression of JAZF1 in protein level displayed the correlations with Vimentin but inversely with E-cadherin. Conclusions Increased miR-1275 expression inhibited GC metastasis by regulating vimentin/E-cadherin via direct suppression of JAZF1expression, suggesting that miR-1275 is a tumour-suppressor miRNA with the potential as a prognostic biomarker or therapeutic target in GC. Electronic supplementary material The online version of this article (10.1186/s12885-019-5929-1) contains supplementary material, which is available to authorized users.

The spin polarization in nonmagnetic materials is conventionally attributed to the outcome of spin-orbit coupling when the global inversion symmetry is broken. The recently discovered hidden spin polarization indicates that a specific atomic site asymmetry could also induce measurable spin polarization, leading to a paradigm shift in research on centrosymmetric crystals for potential spintronic applications. Here, combining spin- and angle-resolved photoemission spectroscopy and theoretical calculations, we report distinct spin-momentum-layer locking phenomena in a centrosymmetric, layered material, BiOI. The measured spin is highly polarized along the Brillouin zone boundary, while the same effect almost vanishes around the zone center due to its nonsymmorphic crystal structure. Our work demonstrates the existence of momentum-dependent hidden spin polarization and uncovers the microscopic mechanism of spin, momentum, and layer locking to each other, thus shedding light on the design metrics for future spintronic materials.

In this work, we demonstrate that the nonsuperconducting single-layer FeTe can become superconducting when its structure is properly tuned by epitaxially growing it on Bi2Te3 thin films. The properties of the single-layer FeTe deviate strongly from its bulk counterpart, as evidenced by the emergence of a large superconductivity gap (3.3 meV) and an apparent 8 × 2 superlattice (SL). Our first-principles calculations indicate that the 8 × 2 SL and the emergence of the novel superconducting phase are essentially the result of the structural change in FeTe due to the presence of the underlying Bi2Te3 layer. The structural change in FeTe likely suppresses the antiferromagnetic order in the FeTe and leads to superconductivity. Our work clearly demonstrates that moire pattern engineering in a heterostructure is a reachable dimension for investigating novel materials and material properties.

Layered honeycomb lattice antiferromagnetic $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Ru}{\mathrm{Cl}}_{3}$ has been studied intensively recently as a Kitaev spin liquid candidate. Here we present strong evidence that this material host realistic Weyl fermions derived from Cl $2p$ electrons. Our theoretical analysis suggests the existence of quadratic Weyl fermions without spin-orbit coupling and linear Weyl fermion with spin-orbit coupling. Angle-resolved photoemission spectroscopy with systematic photon energy-dependent measurements demonstrates that this Weyl cone possesses linear dispersion at bulk Brillouin zone center along all the three reciprocal directions and hyperbolic dispersion off center. Our work reveals the rich topological physics lying in the band structure of Kitaev QSL candidates and will stimulate further investigation not only limited to $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Ru}{\mathrm{Cl}}_{3}$ but also honeycomb iridate family of materials.

The recent discovery of superconductivity in doped infinite-layer nickelates has stimulated intensive interest, especially for similarities and differences compared to that in cuprate superconductors. In contrast to cuprates, although earlier magnetization measurement reveals a Curie-Weiss-like behavior in undoped infinite-layer nickelates, there is no magnetic ordering observed by elastic neutron scattering down to liquid helium temperature. Until now, the nature of the magnetic ground state in undoped infinite-layer nickelates was still elusive. Here, we perform a nuclear magnetic resonance (NMR) experiment through 139La nuclei to study the intrinsic spin susceptibility of infinite-layer LaNiO2. First, the signature for magnetic ordering or freezing is absent in the 139La NMR spectrum down to 0.24 K, which unambiguously confirms a paramagnetic ground state in LaNiO2. Second, a pseudogap-like behavior instead of Curie-Weiss-like behavior is observed in both the temperature-dependent Knight shift and nuclear spin-lattice relaxation rate (1/T1), which is widely observed in both underdoped cuprates and iron-based superconductors. Furthermore, the scaling behavior between the Knight shift and 1/T1T has also been discussed. Finally, the present results imply a considerable exchange interaction in infinite-layer nickelates, which sets a strong constraint for the proposed theoretical models., 14 pages, 4 figures, accepted by Physical Review Letters

Beyond the absence of long-range magnetic orders, the most prominent feature of the elusive quantum spin liquid (QSL) state is the existence of fractionalized spin excitations, i.e., spinons. When the system orders, the spin-wave excitation appears as the bound state of the spinon-antispinon pair. Although scarcely reported, a direct comparison between similar compounds illustrates the evolution from spinon to magnon. Here, we perform the Raman scattering on single crystals of two quantum kagome antiferromagnets, of which one is the kagome QSL candidate Cu3Zn(OH)6FBr, and another is an antiferromagnetically ordered compound EuCu3(OH)6Cl3. In Cu3Zn(OH)6FBr, we identify a unique one spinon-antispinon pair component in the E2g magnetic Raman continuum, providing strong evidence for deconfined spinon excitations. In contrast, a sharp magnon peak emerges from the one-pair spinon continuum in the Eg magnetic Raman response once EuCu3(OH)6Cl3 undergoes the antiferromagnetic order transition. From the comparative Raman studies, we can regard the magnon mode as the spinon-antispinon bound state, and the spinon confinement drives the magnetic ordering., Spinon excitations of a Kagome quantum spin liquid are expected to give rise to a magnetic continuum in Raman spectroscopy. Here, the authors report a magnetic Raman continuum in the Kagome spin liquid candidate Cu3Zn(OH)6FBr, in contrast to a sharp magnon Raman peak in the Kagome antiferromagnet EuCu3(OH)6Cl3.

We investigated the evolution of ferromagnetism in layered Fe

Raman spectroscopy has been applied to investigate the lattice and magnetic excitations of the honeycomb Kitaev material $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{L}{\mathrm{i}}_{2}\mathrm{Ir}{\mathrm{O}}_{3}$. The temperature-dependent Raman spectra give evidence for an unusual magnetic excitation, typified by a broad continuum. The integrated intensity of this Raman continuum does not follow the bosonic statistics expected for the conventional insulating magnets, which indicates the emergence of itinerant Majorana fermions from spin fractionalization in $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{L}{\mathrm{i}}_{2}\mathrm{Ir}{\mathrm{O}}_{3}$. In addition, the Raman results under pressures resolve one critical pressure at ${P}_{c}=4.1\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$ with structural and magnetic phase transitions, signaled by the in-plane Ir-Ir bond dimerization and magnetic collapse, and the system turns into a correlated band insulator above ${P}_{c}$.

Topological insulator with antiferromagnetic order can serve as an ideal platform to realize axion electrodynamics. In this paper, we report a systematic study of the axion topological insulator candidate ${\mathrm{EuIn}}_{2}{\mathrm{As}}_{2}$. A linear energy dispersion across the Fermi level reveals a hole-type Fermi pocket. The orientation of the magnetic moment for ground state is determined within the $ab$-plane by anisotropic magnetic behavior. Besides long-range antiferromagnetic order, magnetization and magnetotransport measurements indicate existence of the ferromagnetic orders and ferromagnetic correlation, suggesting the formation of the magnetic polarons. These ferromagnetic clusters can persist above the antiferromagnetic transition leading to unconventional transport properties. Our results suggest multiple magnetic orders and states in ${\mathrm{EuIn}}_{2}{\mathrm{As}}_{2}$, which is vital to understanding its topological nature.

Recently ${\mathrm{H}}_{3}{\mathrm{LiIr}}_{2}{\mathrm{O}}_{6}$ has been reported as a spin-orbital entangled quantum spin liquid (QSL) [K. Kitagawa et al., Nature (London) 554, 341 (2018)], albeit its connection to Kitaev QSL has not been yet identified. To unveil the related Kitaev physics, we perform Raman spectroscopy studies on single-crystalline ${\mathrm{H}}_{3}{\mathrm{LiIr}}_{2}{\mathrm{O}}_{6}$ samples. We implement a soft chemical replacement of ${\mathrm{Li}}^{+}$ with ${\mathrm{H}}^{+}$ from $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Li}}_{2}{\mathrm{IrO}}_{3}$ single crystals to synthesize the single crystal samples of the iridate second-generation ${\mathrm{H}}_{3}{\mathrm{LiIr}}_{2}{\mathrm{O}}_{6}$. The unusual phonon broadening in ${\mathrm{H}}_{3}{\mathrm{LiIr}}_{2}{\mathrm{O}}_{6}$ implies the random positions of the substituted ${\mathrm{H}}^{+}$. As well as the lattice dynamics, Raman spectroscopy can also be used to diagnose the QSL state since the magnetic Raman continuum arises from a process involving pairs of fractionalized Majorana fermionic excitation in a pure Kitaev model. We observe a broad dome-shaped magnetic continuum in ${\mathrm{H}}_{3}{\mathrm{LiIr}}_{2}{\mathrm{O}}_{6}$, in line with theoretical expectations for the two-spin process in the Kitaev QSL. The possible scenario of the structural disordered magnet for the magnetic Raman continuum is also discussed.

How an interfacial superconductivity emerges during the nucleation and epitaxy is of great importance not only for unveiling the physical insights but also for finding a feasible way to tune the superconductivity via interfacial engineering. In this work, we report the nanoscale creation of a robust and relatively homogeneous interfacial superconductivity (

The authors combined the Heyd-Scuseria-Ernzerhof hybrid density functional first-principles calculation and the cluster exact diagonalization to study the strongly correlated electronic structures of the nickelate oxides Nd1\ensuremath{-}xSrxNiO2 and derive the effective one-band Hamiltonian model for the superconductivity.

We report the magnetotransport properties of $\mathrm{MnB}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{4}$ thin flakes through gate modulation at low temperatures. Under in-plane magnetic field, a large negative magnetoresistance (MR) maintains up to 10 T, which is related to the suppression of spin scattering when the magnetic order is gradually forced into the ferromagnetic (FM) state. Under perpendicular magnetic field, a steep resistance decrease is observed around \ensuremath{\sim}3 T, corresponding to the transition from an antiferromagnetic (AFM) to a canted AFM (CAFM) state. Due to the net Berry curvature, a notable anomalous Hall effect is observed and can be effectively tuned by gate voltages. The enhanced Hall coefficient would emerge under high magnetic fields when the Fermi level is close to the charge neutral point. Moreover, a transition from negative to positive MR is obtained when increasing the magnetic field. A large linear positive MR occurs around $\ensuremath{\sim}8\phantom{\rule{0.16em}{0ex}}\mathrm{T}$, corresponding to the CAFM-FM transition. The nonsaturated positive MR here may have a similar mechanism to the one in Weyl semimetals, revealing the strong combination between topology and magnetism in $\mathrm{MnB}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{4}$.

The layered MnBi2nTe3n+1 family represents the first intrinsic antiferromagnetic topological insulator (AFM TI, protected by a combination symmetry ) ever discovered, providing an ideal platform to explore novel physics such as quantum anomalous Hall effect at elevated temperature and axion electrodynamics. Recent angle-resolved photoemission spectroscopy (ARPES) experiments on this family have revealed that all terminations exhibit (nearly) gapless topological surface states (TSSs) within the AFM state, violating the definition of the AFM TI, as the surfaces being studied should be -breaking and opening a gap. Here we explain this curious paradox using a surface-bulk band hybridization picture. Combining ARPES and first-principles calculations, we prove that only an apparent gap is opened by hybridization between TSSs and bulk bands. The observed (nearly) gapless features are consistently reproduced by tight-binding simulations where TSSs are coupled to a Rashba-split bulk band. The Dirac-cone-like spectral features are actually of bulk origin, thus not sensitive to the-breaking at the AFM surfaces. This picture explains the (nearly) gapless behaviour found in both Bi2Te3- and MnBi2Te4-terminated surfaces and is applicable to all terminations of MnBi2nTe3n+1 family. Our findings highlight the role of band hybridization, superior to magnetism in this case, in shaping the general surface band structure in magnetic topological materials for the first time., 18 pages, 4 figures

A topological insulator with magnetic elements shows surprising conductive behavior on its surface, presenting either a hurdle to realizing exotic quantum phenomena or a boon to devices with new charge transport mechanisms.

The antiferromagnetism in $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Cu}}_{3}\mathrm{Mg}{(\mathrm{OH})}_{6}{\mathrm{Br}}_{2}$ was studied by magnetic-susceptibility, specific-heat, and neutron-diffraction measurements. The crystal structure consists of ${\mathrm{Cu}}^{2+}$ kagome layers with ${\mathrm{Mg}}^{2+}$ ions occupying the centers of the hexagons, separated by ${\mathrm{Br}}^{1\ensuremath{-}}$ ions. The magnetic system orders antiferromagnetically at 5.4 K with the magnetic moments aligned ferromagnetically within the kagome planes. The ordered moment is $0.94{\ensuremath{\mu}}_{B}$, suggesting little quantum and geometrical fluctuations. By comparing the magnetic and specific-heat properties with those of the haydeeite, we suggest that $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Cu}}_{3}\mathrm{Mg}{(\mathrm{OH})}_{6}{\mathrm{Br}}_{2}$ may be described by the two-dimensional spin-$1/2$ Heisenberg kagome model and is in the region of the ferromagnetic-order side of the phase diagram.

Objective: Mammalian target of rapamycin complex 1 (mTORC1) plays an important role in maintaining proper cellular functions in gastric cancer (GC). Previous studies demonstrated genetic variants within mTORC1 genes were associated with GC risk. However, no studies reported the associations between genetic variants within mTORC1 genes and GC prognosis. Herein, we firstly assessed the associations of genetic variants of mTORC1 genes with overall survival (OS) of GC in Chinese populations. Methods: We genotyped eight single nucleotide polymorphisms (SNPs) in mTORC1 genes (i.e., rs2536 T>C and rs1883965 G>A for mTOR, rs3160 T>C and rs26865 A>G for MLST8, rs3751934 C>A, rs1062935 T>C, rs3751932 T>C and rs12602885 G>A for RPTOR) by the TaqMan method in 197 Chinese GC patients who had surgical resection in Xinhua Hospital. We conducted Kaplan-Meier survival plots and Cox hazards regression analysis to explore the associations of these SNPs with OS. Results: The single-locus analysis indicated that RPTOR rs1062935 T>C was associated with an increased risk of poor GC prognosis (CC vs. TT/TC: adjusted Hazard ratio (HR) = 1.71, 95% confidence interval (CI) = 1.04-2.82). The combined analysis of all eight SNPs showed that patients with more than three risk genotypes significantly increased risk of death (adjusted HR = 2.44, 95% CI = 1.30-4.58), when compared to those with three or less risk genotypes. Conclusions: Our findings indicated that genetic variants within mTORC1 genes may predict GC prognosis in Chinese populations. The results need to be validated in future studies with larger sample sizes.