Explore the vast range of titles available.

Investigations of two-dimensional transition-metal chalcogenides (TMCs) have recently revealed interesting physical phenomena, including the quantum spin Hall effect 1 , 2 , valley polarization 3 , 4 and two-dimensional superconductivity 5 , suggesting potential applications for functional devices 6 – 10 . However, of the numerous compounds available, only a handful, such as Mo- and W-based TMCs, have been synthesized, typically via sulfurization 11 – 15 , selenization 16 , 17 and tellurization 18 of metals and metal compounds. Many TMCs are difficult to produce because of the high melting points of their metal and metal oxide precursors. Molten-salt-assisted methods have been used to produce ceramic powders at relatively low temperature 19 and this approach 20 was recently employed to facilitate the growth of monolayer WS 2 and WSe 2 . Here we demonstrate that molten-salt-assisted chemical vapour deposition can be broadly applied for the synthesis of a wide variety of two-dimensional (atomically thin) TMCs. We synthesized 47 compounds, including 32 binary compounds (based on the transition metals Ti, Zr, Hf, V, Nb, Ta, Mo, W, Re, Pt, Pd and Fe), 13 alloys (including 11 ternary, one quaternary and one quinary), and two heterostructured compounds. We elaborate how the salt decreases the melting point of the reactants and facilitates the formation of intermediate products, increasing the overall reaction rate. Most of the synthesized materials in our library are useful, as supported by evidence of superconductivity in our monolayer NbSe 2 and MoTe 2 samples 21 , 22 and of high mobilities in MoS 2 and ReS 2 . Although the quality of some of the materials still requires development, our work opens up opportunities for studying the properties and potential application of a wide variety of two-dimensional TMCs. Molten-salt-assisted chemical vapour deposition is used to synthesize a wide variety of two-dimensional transition-metal chalcogenides.

Two-dimensional (2D) materials with multiphase, multielement crystals such as transition metal chalcogenides (TMCs) (based on V, Cr, Mn, Fe, Cd, Pt and Pd) and transition metal phosphorous chalcogenides (TMPCs) offer a unique platform to explore novel physical phenomena. However, the synthesis of a single-phase/single-composition crystal of these 2D materials via chemical vapour deposition is still challenging. Here we unravel a competitive-chemical-reaction-based growth mechanism to manipulate the nucleation and growth rate. Based on the growth mechanism, 67 types of TMCs and TMPCs with a defined phase, controllable structure and tunable component can be realized. The ferromagnetism and superconductivity in FeXy can be tuned by the y value, such as superconductivity observed in FeX and ferromagnetism in FeS2 monolayers, demonstrating the high quality of as-grown 2D materials. This work paves the way for the multidisciplinary exploration of 2D TMPCs and TMCs with unique properties.A competitive-chemical-reaction-based growth mechanism by controlling the kinetic parameters can easily realize the growth of transition metal chalcogenides and transition metal phosphorous chalcogenides with different compositions and phases.

The discovery of monolayer superconductors bears consequences for both fundamental physics and device applications. Currently, the growth of superconducting monolayers can only occur under ultrahigh vacuum and on specific lattice-matched or dangling bond-free substrates, to minimize environment- and substrate-induced disorders/defects. Such severe growth requirements limit the exploration of novel two-dimensional superconductivity and related nanodevices. Here we demonstrate the experimental realization of superconductivity in a chemical vapour deposition grown monolayer material—NbSe 2 . Atomic-resolution scanning transmission electron microscope imaging reveals the atomic structure of the intrinsic point defects and grain boundaries in monolayer NbSe 2 , and confirms the low defect concentration in our high-quality film, which is the key to two-dimensional superconductivity. By using monolayer chemical vapour deposited graphene as a protective capping layer, thickness-dependent superconducting properties are observed in as-grown NbSe 2 with a transition temperature increasing from 1.0 K in monolayer to 4.56 K in 10-layer. Two-dimensional superconductors will likely have applications not only in devices, but also in the study of fundamental physics. Here, Wang et al. demonstrate the CVD growth of superconducting NbSe2 on a variety of substrates, making these novel materials increasingly accessible.

Two-dimensional transition metal dichalcogenides with peculiar spin–orbit coupling may lead to exotic phenomena. Here, the authors report a large in-plane upper critical field with a two-fold symmetry, suggesting a novel asymmetric spin–orbit coupling in few-layer 1T d-MoTe2.

Two-dimensional transition metal dichalcogenides MX 2 ( M  = W, Mo, Nb, and X  = Te, Se, S) with strong spin–orbit coupling possess plenty of novel physics including superconductivity. Due to the Ising spin–orbit coupling, monolayer NbSe 2 and gated MoS 2 of 2 H structure can realize the Ising superconductivity, which manifests itself with in-plane upper critical field far exceeding Pauli paramagnetic limit. Surprisingly, we find that a few-layer 1 T d structure MoTe 2 also exhibits an in-plane upper critical field which goes beyond the Pauli paramagnetic limit. Importantly, the in-plane upper critical field shows an emergent two-fold symmetry which is different from the isotropic in-plane upper critical field in 2 H transition metal dichalcogenides. We show that this is a result of an asymmetric spin–orbit coupling in 1 T d transition metal dichalcogenides. Our work provides transport evidence of a new type of asymmetric spin–orbit coupling in transition metal dichalcogenides which may give rise to novel superconducting and spin transport properties. Two-dimensional transition metal dichalcogenides with peculiar spin–orbit coupling may lead to exotic phenomena. Here, the authors report a large in-plane upper critical field with a two-fold symmetry, suggesting a novel asymmetric spin–orbit coupling in few-layer 1 T d -MoTe 2 .

Alzheimer’s disease (AD) is ranked as the third-most expensive illness and sixth leading cause of mortality. It is associated with the deposition of extracellular amyloid-β (Aβ) in neural plaques (NPs), as well as intracellular hyperphosphorylated tau proteins that form neurofibrillary tangles (NFTs). As a new target in regulating neuroinflammation in AD, triggering receptor expressed on myeloid cells 2 (TREM2) is highly and exclusively expressed on the microglial surface. TREM2 interacts with adaptor protein DAP12 to initiate signal pathways that mainly dominant microglia phenotype and phagocytosis mobility. Furthermore, TREM2 gene mutations confer increased AD risk, and TREM2 deficiency exhibits more dendritic spine loss around neural plaques. Mechanisms for regulating TREM2 to alleviate AD has evolved as an area of AD research in recent years. Current medications targeting Aβ or tau proteins are unable to reverse AD progression. Emerging evidence implicating neuroinflammation may provide novel insights, as early microglia-related inflammation can be induced decades prior to the commencement of AD-related cognitive damage. Physical exercise can exert a neuroprotective effect over the course of AD progression. This review aims to (1) summarize the pathogenesis of AD and recent updates in the field, (2) assess the concept that AD cognitive impairment is closely correlated with microglia-related inflammation, and (3) review TREM2 functions and its role between exercise and AD, which is likely to be an ideal candidate target.

Fractional quantum Hall (FQH) states are exotic quantum many-body phases whose elementary charged excitations are anyons obeying fractional braiding statistics. While most FQH states are believed to have Abelian anyons, the Moore–Read type states with even denominators – appearing at half filling of a Landau level (LL) – are predicted to possess non-Abelian excitations with appealing potential in topological quantum computation. These states, however, depend sensitively on the orbital contents of the single-particle LL wavefunctions and the LL mixing. Here we report magnetotransport measurements on Bernal-stacked trilayer graphene, whose multiband structure facilitates interlaced LL mixing, which can be controlled by external magnetic and displacement fields. We observe robust FQH states including even-denominator ones at filling factors ν  = − 9/2, − 3/2, 3/2 and 9/2. In addition, we fine-tune the LL mixing and crossings to drive quantum phase transitions of these half-filling states and neighbouring odd-denominator ones, exhibiting related emerging and waning behaviour. The fractional quantum Hall effect offers a potential platform to harness non-Abelian anyons. Here, the authors report fractional quantum Hall states in trilayer graphene and drive quantum phase transitions between neighbouring states.

Edge states in topological systems have attracted great interest due to their robustness and linear dispersions. Here a superconducting-proximitized edge interferometer is engineered on a topological insulator Ta 2 Pd 3 Te 5 with asymmetric edges to realize the interfering Josephson diode effect (JDE), which hosts many advantages, such as the high efficiency as much as 73% at tiny applied magnetic fields with an ultra-low switching power around picowatt. As an important element to induce such JDE, the second-order harmonic in the current-phase relation is also experimentally confirmed by half-integer Shapiro steps. The interfering JDE is also accompanied by the antisymmetric second harmonic transport, which indicates the corresponding asymmetry in the interferometer, as well as the polarity of JDE. This edge interferometer offers an effective method to enhance the performance of JDE, and boosts great potential applications for future superconducting quantum devices. Applications of edge states are rare. Here the authors utilize asymmetric edge states in the topological material Ta 2 Pd 3 Te 5 to achieve the interfering Josephson diode effect, exhibiting high efficiency with ultra-low switching power at very small magnetic fields.

Topological materials with boundary (surface/edge/hinge) states have attracted tremendous research interest. Additionally, unconventional (obstructed atomic) materials have recently drawn lots of attention owing to their obstructed boundary states. Experimentally, Josephson junctions (JJs) constructed on materials with boundary states produce the peculiar boundary supercurrent, which was utilized as a powerful diagnostic approach. Here, we report the observations of boundary supercurrent in NiTe 2 -based JJs. Particularly, applying an in-plane magnetic field along the Josephson current can rapidly suppress the bulk supercurrent and retain the nearly pure boundary supercurrent, namely the magnetic field filtering of supercurrent. Further systematic comparative analysis and theoretical calculations demonstrate the existence of unconventional nature and obstructed hinge states in NiTe 2 , which could produce hinge supercurrent that accounts for the observation. Our results reveal the probable hinge states in unconventional metal NiTe 2 , and demonstrate in-plane magnetic field as an efficient method to filter out the bulk contributions and thereby to highlight the hinge states hidden in topological/unconventional materials. The authors study Josephson junctions where the weak link is a NiTe 2 flake. They find that in-plane magnetic field in a particular direction causes the supercurrent to concentrate in the edges of the flake, excluding the bulk. They further argue that the supercurrent is carried by higher-order hinge states.

The interplay between topology and interaction always plays an important role in condensed matter physics and induces many exotic quantum phases, while rare transition metal layered material (TMLM) has been proved to possess both. Here we report a TMLM Ta 2 Pd 3 Te 5 has the two-dimensional second-order topology (also a quadrupole topological insulator) with correlated edge states - Luttinger liquid. It is ascribed to the unconventional nature of the mismatch between charge- and atomic- centers induced by a remarkable double-band inversion. This one-dimensional protected edge state preserves the Luttinger liquid behavior with robustness and universality in scale from micro- to macro- size, leading to a significant anisotropic electrical transport through two-dimensional sides of bulk materials. Moreover, the bulk gap can be modulated by the thickness, resulting in an extensive-range phase diagram for Luttinger liquid. These provide an attractive model to study the interaction and quantum phases in correlated topological systems. The interplay of electronic correlations and topology has been a forefront topic in condensed matter physics. Wang et al. present evidence of a correlated topological edge state supporting the Luttinger liquid behaviour in the candidate quadrupole topological insulator Ta 2 Pd 3 Te 5 .