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The van der Waals antiferromagnetic topological insulator MnBi2Te4 represents a promising platform for exploring the layer-dependent magnetism and topological states of matter. Recently observed discrepancies between magnetic and transport properties have aroused controversies concerning the topological nature of MnBi2Te4 in the ground state. In this article, we demonstrate that fabrication can induce mismatched even-odd layer dependent magnetotransport in few-layer MnBi2Te4. We perform a comprehensive study of the magnetotransport properties in 6- and 7-septuple-layer MnBi2Te4, and reveal that both even- and odd-number-layer device can show zero Hall plateau phenomena in zero magnetic field. Importantly, a statistical survey of the optical contrast in more than 200 MnBi2Te4 flakes reveals that the zero Hall plateau in odd-number-layer devices arises from the reduction of the effective thickness during the fabrication, a factor that was rarely noticed in previous studies of 2D materials. Our finding not only provides an explanation to the controversies regarding the discrepancy of the even-odd layer dependent magnetotransport in MnBi2Te4, but also highlights the critical issues concerning the fabrication and characterization of 2D material devices. MnBi2Te4 is an antiferromagnetic topological insulator. This combination of magnetic ordering and topological properties has resulted in intense interest, however, like many van der Waals materials, experimental results are hampered by fabrication difficulties. Here, Li, Wang, Lian et al. show that the fabrication process itself can result in mismatched thickness dependence of magneto-transport measurements. ' [ABSTRACT FROM AUTHOR]

Driven by the minimization of total energy, the multi-domain morphology is preferred in as-grown ferroelectrics to reduce the depolarization and strain energy during the paraelectric to ferroelectric phase transition. However, the complicated multi-domain is not desirable for certain high-performance ferroelectric electro-optic devices. In this work, we achieve a reproducible and stable large-area monodomain in as-grown bulk ferroelectric single crystal Sn 2 P 2 S 6 . The monodomain dominates the entire single crystal, which is attributed to the internal charge carriers from the photoexcited disproportionation reaction of Sn ions. The charge carriers effectively screen the depolarization field and therefore decrease the depolarization energy and facilitate the formation of monodomain. This work offers a potential approach for engineering bulk ferroelectrics with a stable monodomain, which is desirable for the high-performance ferroelectric electro-optic devices. [ABSTRACT FROM AUTHOR]

One of the greatest triumph of condensed matter physics in the past ten years is the classification of materials by the principle of topology. The existence of topological protected dissipationless surface state makes topological insulators great potential for applications and hotly studied. However, compared with the prosperity of strong topological insulators, theoretical predicted candidate materials and experimental confirmation of weak topological insulators (WTIs) are both extremely rare. By combining systematic first-principles calculation and angle-resolved photoemission spectroscopy measurements, we have studied the electronic structure of the dark surface of the WTI candidate Zintl Ba3Cd2Sb4 and another related material Ba3Cd2As4. The existence of two Dirac surface states on specific side surfaces predicted by theoretical calculations and the observed two band inversions in the Brillouin zone give strong evidence to prove that the Ba3Cd2Sb4 is a WTI. The spectroscopic characterization of this Zintl Ba3Cd2N4 (N = As and Sb) family materials will facilitate applications of their novel topological properties. [ABSTRACT FROM AUTHOR]

In transition-metal dipnictides TmPn2 (Tm = Ta and Nb; Pn = P, As, and Sb), the origin of extremely large magnetoresistance (XMR) is yet to be studied by the direct visualization of the experimental band structures. Here, using angle-resolved photoemission spectroscopy, we map out the three-dimensional electronic structure of NbAs2. The open-orbit topology contributes to a non-negligible part of the Fermi surfaces (FSs), like that of the isostructural compound MoAs2, where the open FS is proposed to likely explain the origin of XMR. We further demonstrate the observation of open characters in the overall FSs of W2As3, which is also a XMR semimetal with the same space group of C12/m1 as the TmPn2 family and MoAs2. Our results suggest that the open-orbit FS topology may be a shared feature between XMR materials with the space group of C12/m1 and, thus, could possibly play a role in determining the corresponding XMR effect together with the electron–hole compensation. [ABSTRACT FROM AUTHOR]

Developing a single-phase self-rectifying memristor with the continuously tunable feature is structurally desirable and functionally adaptive to dynamic environmental stimuli variations, which is the pursuit of further smart memristors and neuromorphic computing. Herein, we report a van der Waals ferroelectric CuInP2S6 as a single memristor with superior continuous modulation of current and self-rectifying to different bias stimuli (sweeping speed, direction, amplitude, etc.) and external mechanical load. The synergetic contribution of controllable Cu+ ions migration and interfacial Schottky barrier is proposed to dynamically control the current flow and device performance. These outstanding sensitive features make this material possible for being superior candidate for future smart memristors with bidirectional operation mode and strong recognition to input faults and variations. Developing a single-phase self-rectifying memristor is desirable and functionally adaptive to dynamic environmental stimuli variations. Here, the authors report a single phase CuInP2S6 based memristor with continuously tunable current rectifying. [ABSTRACT FROM AUTHOR]

We report the doping effects of cobalt on van der Waals (vdW) magnet Fe5GeTe2. A series of (Fe1−xCox)5GeTe2 (0 ≤ x ≤ 0.44) single crystals have been grown, and their structural, magnetic, and transport properties are investigated. For x = 0.20, the Curie temperature TC increases from 276 K to 337 K. Moreover, the magnetic easy axis is reoriented to the ab-plane from the c-axis in undoped Fe5GeTe2 with largely enhanced magnetic anisotropy. A complex magnetic phase diagram is identified on the higher doping side. The x = 0.44 crystal first orders ferromagnetically at TC = 363 K and then undergoes an antiferromagnetic (AFM) transition at TN = 335 K. Furthermore, magnetic-field-induced spin-flop transitions are observed for the AFM ground state. Our work reveals (Fe1−xCox)5GeTe2 as promising candidates for developing spin-related applications and proposes a method to engineer the magnetic properties of the vdW magnet. [ABSTRACT FROM AUTHOR]

Reactions of trinickel complex of tripodal tris-tacn ligand N(CH2- m-C6H4-CH2tacn)3 ( L, tacn=1,4,7-triazacyclononane) in acetonitrile-methanol solution with and without phosphate led to two complexes of distinct nuclearities, [(NiIICl)3(CH3OH)3(HPO4) L](PF6) (Ni3, 1) and [(NiII5(CN)4(H2O)8Cl)6 L8]Cl30 (Ni30, 2). Ligand L takes upward and downward conformation in the structure of 1 and 2, respectively. It is proposed that phosphate directs the upward conformation of Ni3 L to form 1. In the absence of phosphate, Ni3 L assembles with cyanide ions, which are formed by Ni-catalyzed C−CN bond cleavage of acetonitrile, to give a nano-sized Ni30 cage. Complex 2 represents a discrete truncated octahedron cage assembled with [Ni5(CN)4]6+ squares and large and flexible triangular ligands, which is scarcely observed for self-assembled metal-organic cages. The magnetic properties of 1 and 2 were examined, showing intriguing magnetic properties. [ABSTRACT FROM AUTHOR]

A fast and furnace-free method of combustion synthesis is employed for the first time to synthesize iron-based superconductors. Using this method, Fe 1.1 Se 1 − x Te x (0 ≤ x ≤ 1) samples can be prepared from self-sustained reactions of element powders in only tens of seconds. The obtained Fe 1.1 Se 1 − x Te x samples show clear zero resistivity and corresponding magnetic susceptibility drop at around 10–14 K. The Fe 1.1 Se 0.33 Te 0.67 sample shows the highest onset T c of about 14 K, and its upper critical field is estimated to be approximately 54T. Compared with conventional solid state reaction for preparing polycrystalline FeSe samples, combustion synthesis exhibits much-reduced time and energy consumption, but offers comparable superconducting properties. It is expected that the combustion synthesis method is available for preparing plenty of iron-based superconductors, and in this direction further work is being in progress. [ABSTRACT FROM AUTHOR]

One of the greatest triumph of condensed matter physics in the past ten years is the classification of materials by the principle of topology. The existence of topological protected dissipationless surface state makes topological insulators great potential for applications and hotly studied. However, compared with the prosperity of strong topological insulators, theoretical predicted candidate materials and experimental confirmation of weak topological insulators (WTIs) are both extremely rare. By combining systematic first-principles calculation and angle-resolved photoemission spectroscopy measurements, we have studied the electronic structure of the dark surface of the WTI candidate Zintl Ba3Cd2Sb4 and another related material Ba3Cd2As4. The existence of two Dirac surface states on specific side surfaces predicted by theoretical calculations and the observed two band inversions in the Brillouin zone give strong evidence to prove that the Ba3Cd2Sb4 is a WTI. The spectroscopic characterization of this Zintl Ba3Cd2N4 (N = As and Sb) family materials will facilitate applications of their novel topological properties. [ABSTRACT FROM AUTHOR]

What Is Already Known About This Topic?: Aerosol transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) via sanitary pipelines in high-rise buildings is possible, however, there is a lack of experimental evidence., What Is Added by This Report?: The field simulation experiment confirmed the existence of a vertical aerosol transmission pathway from toilet flush-soil stack-floor drains without water seal. This report provided experimental evidence for vertical aerosol transmission of clustered outbreaks on 18 floors of a 33-story residential building., What Are the Implications for Public Health Practice?: The water seal on floor drains is a necessary barrier to prevent the risk of vertical aerosol transmission of infectious disease pathogens in buildings. It is necessary not only to have a U-shaped trap in the drainage pipe, but also to be filled with water regularly., Competing Interests: No conflicts of interest., (Copyright and License information: Editorial Office of CCDCW, Chinese Center for Disease Control and Prevention 2022.)

RhSn is a topological semimetal with chiral fermions. At ambient pressure, it exhibits large positive magnetoresistance (MR) and field-induced resistivity upturn at low temperatures. Here we report on the electrical transport properties of RhSn single crystal under various pressures. We find that with increasing pressure the temperature-dependent resistivity ρ ( T ) of RhSn varies minutely, whereas the value of MR at low temperatures decreases significantly. The ρ ( T ) data was fitted with the Bloch-Grüneisen model and the Debye temperature was extracted. Analyses of the nonlinear Hall conductivity with two-band model indicate that the carrier concentrations do not change significantly with pressure, but the mobilities for both electron and hole carriers are reduced monotonically, which can account for the significant reduction of MR under high pressures., (© 2020 IOP Publishing Ltd.)

van der Waals (vdW) layered materials have rather weaker interlayer bonding than the intralayer bonding, therefore the exfoliation along the stacking direction enables the achievement of monolayer or few layers vdW materials with emerging novel physical properties and functionalities. The ferroelectricity in vdW materials recently attracts renewed interest for the potential use in high-density storage devices. With the thickness becoming thinner, the competition between the surface energy, depolarization field, and interfacial chemical bonds may give rise to the modification of ferroelectricity and crystalline structure, which has limited investigations. In this work, combining the piezoresponse force microscope scanning, contact resonance imaging, the existence of the intrinsic in-plane polarization in vdW ferroelectrics CuInP 2 S 6 single crystals is reported, whereas below a critical thickness between 90 and 100 nm, the in-plane polarization disappears. The Young's modulus also shows an abrupt stiffness at the critical thickness. Based on the density functional theory calculations, these behaviors are ascribed to a structural phase transition from monoclinic to trigonal structure, which is further verified by transmission electron microscope technique. These findings demonstrate the foundational importance of structural phase transition for enhancing the rich functionality and broad utility of vdW ferroelectrics., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The study aims to determine the spatial and temporal variation of a longevous region and explore the correlation between longevity and socioeconomic development. Population data at the township level were obtained from the last four population censuses (1982-2010). Five main lifespan indicators and the Human Development Index (HDI) were calculated. Getis-Ord G*, Gravity modeling, and Pearson's r between lifespan indicators and HDI were applied. In this study, a stable longevous gathering area was discovered in Hechi during different periods. Under the influence of social and economic development, more longevous areas appeared. However, the effects of genetic and natural environmental factors on longevity were always dominant in this remote and mountainous city. Furthermore, longevity indicators lacked any significant correlation with life expectancy. No significant positive correlation was detected between lifespan indicators and HDI. Thus, we conclude that lifespan indicators can determine the spatial distribution and variation pattern of longevity from multiple dimensions. The geographical scope of longevity in Hechi City is gradually expanding, and significant spatial clustering was detected in southwestern, southern, and eastern parts of Hechi. This study also found that social economic development is likely to have a certain impact on new longevous areas, but their role on extreme longevity is not significant., Competing Interests: The authors declare no conflict of interest.

Reactions of trinickel complex of tripodal tris-tacn ligand N(CH 2 -m-C 6 H 4 -CH 2 tacn) 3 (L, tacn=1,4,7-triazacyclononane) in acetonitrile-methanol solution with and without phosphate led to two complexes of distinct nuclearities, [(Ni II Cl) 3 (CH 3 OH) 3 (HPO 4 )L](PF 6 ) (Ni 3 , 1) and [(Ni II 5 (CN) 4 (H 2 O) 8 Cl) 6 L 8 ]Cl 30 (Ni 30 , 2). Ligand L takes upward and downward conformation in the structure of 1 and 2, respectively. It is proposed that phosphate directs the upward conformation of Ni 3 L to form 1. In the absence of phosphate, Ni 3 L assembles with cyanide ions, which are formed by Ni-catalyzed C-CN bond cleavage of acetonitrile, to give a nano-sized Ni 30 cage. Complex 2 represents a discrete truncated octahedron cage assembled with [Ni 5 (CN) 4 ] 6+ squares and large and flexible triangular ligands, which is scarcely observed for self-assembled metal-organic cages. The magnetic properties of 1 and 2 were examined, showing intriguing magnetic properties., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: To investigate the risk factors of child lead poisoning in China., Methods: A document retrieval was performed using MeSH (Medical subject heading terms) and key words. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of the studies, and the pooled odd ratios with a 95% confidence interval were used to identify the risk factors. We employed Review Manager 5.2 and Stata 10.0 to analyze the data. Heterogeneity was assessed by both the Chi-square and I² tests, and publication bias was evaluated using a funnel plot and Egger's test., Results: Thirty-four articles reporting 13,587 lead-poisoned children met the inclusion criteria. Unhealthy lifestyle and behaviors, environmental pollution around the home and potential for parents' occupational exposure to lead were risk factors of child lead poisoning in the pooled analyses. Our assessments yielded no severe publication biases., Conclusions: Seventeen risk factors are associated with child lead poisoning, which can be used to identify high-risk children. Health education and promotion campaigns should be designed in order to minimize or prevent child lead poisoning in China.

A new NiO-based material Pb2Ni(PO4)2 was obtained by a conventional solid-state reaction in air. The crystal structure exhibits both corner- and edge-sharing {Ni-O-P} bonds in the system. Magnetic properties were investigated by means of magnetic susceptibility, magnetization, and heat capacity measurements. The results show a typical three-dimensional antiferromagnetic ordering below ~4 K and a field-induced spin-flop transition below the Néel temperature.

Based on an effective Hamiltonian specified in the triangular lattice with possible p(x)+/-ip(y)- or dx(2)(-y(2))+/-id(xy)-wave pairing, which has close relevance to the newly discovered Na0.35CoO2.yH(2)O, the electronic structure of the vortex state is studied by solving the Bogoliubov-de Gennes equations. It is found that p(x)+/-ip(y) wave is favored for the electron doping as the hopping integral t<0. The lowest-lying vortex bound states are found to have, respectively, zero and positive energies for p(x)+/-ip(y)- and dx(2)(-y(2))+/-id(xy)-wave superconductors, whose vortex structures exhibit the intriguing sixfold symmetry. In the presence of strong on-site repulsion, the antiferromagnetic order and local ferromagnetic moment are induced around the vortex cores for the former and the latter, respectively, both of which cause the splitting of the local density of states peaks due to the lifting of spin degeneracy.