High Spatial Resolution 2D Imaging of Current Density and Pressure for Graphene Devices under High Pressure Using Nitrogen-Vacancy Centers in Diamond.

Current density imaging is helpful for discovering interesting electronic phenomena and understanding carrier dynamics, and by combining pressure distributions, several pressure-induced novel physics may be comprehended. In this work, noninvasive, high-resolution two-dimensional images of the current density and pressure gradient for graphene ribbon and hBN-graphene-hBN devices are explored using nitrogen-vacancy (NV) centers in diamond under high pressure. The two-dimensional vector current density is reconstructed by the vector magnetic field mapped by the near-surface NV center layer in the diamond. The current density images accurately and clearly reproduce the complicated structure and current flow of graphene under high pressure. Additionally, the spatial distribution of the pressure is simultaneously mapped, rationalizing the nonuniformity of the current density under high pressure. The current method opens a significant new avenue to investigate electronic transport and conductance variations in two-dimensional materials and electrical devices under high pressure as well as for nondestructive evaluation of semiconductor circuits.

Pressure-induced luminescence evolution of 3,3'-diamino-4,4'-azofurazan: Role of restricting chemical bond vibration and conformational modification.

The luminescence and electronic structure of 3,3'-Diamino-4,4'-azofurazan (DAAzF) were studied under high pressure conditions through experimental and calculation approaches. The transition of π* â†’ π was primarily responsible for DAAzF's broad light emission. Upon applying pressure to DAAzF, high-pressure-stiffened hydrogen-bond interactions enable the restriction of the stretching vibration of NH2 group. The reduced energy loss through nonradiative rotational relaxation and molecular motions lead to a ∼20 times luminescent enhancement of DAAzF from 1 atm to 8.9 GPa. With the further strengthening of interlayer hydrogen bond interactions at higher pressure, the deviation of hydrogen atoms in amino groups from the molecular plane lessens the radiation transition efficiency. In addition, the bending of the C-C-N=N bond further leads to molecular conformation changes at approximately 20.7 GPa, which induces an abrupt redshift and moderate quenching of the luminescence. Furthermore, the band gap of DAAzF is significantly influenced by pressure. As the color undergoes a transition from yellow to red, and becomes darker as the pressure increases, the absorption edge shifted towards red. At 3.4, 9, and 21 GPa, three conformational variations were identified in conjunction with electronic structural alterations.

Dynamic Response of Ion Transport in Nanoconfined Electrolytes.

Ion transport in nanoconfined electrolytes exhibits nonlinear effects caused by large driving forces and pronounced boundary effects. An improved understanding of these impacts is urgently needed to guide the design of key components of the electrochemical energy systems. Herein, we employ a nonlinear Poisson-Nernst-Planck theory to describe ion transport in nanoconfined electrolytes coupled with two sets of boundary conditions to mimic different cell configurations in experiments. A peculiar nonmonotonic charging behavior is discovered when the electrolyte is placed between a blocking electrode and an electrolyte reservoir, while normal monotonic behaviors are seen when the electrolyte is placed between two blocking electrodes. We reveal that impedance shapes depend on the definition of surface charge and the electrode potential. Particularly, an additional arc can emerge in the intermediate-frequency range at potentials away from the potential of zero charge. The obtained insights are instrumental to experimental characterization of ion transport in nanoconfined electrolytes.

Pressure-Modulated Dissolution Behavior of LLM-105 Crystals in High-Temperature Water.

The exploration of the microstructural evolution and reaction kinetics of energetic materials with high-temperature and high-pressure water contributes to the understanding of their microscopic physicochemical origin, which can provide critical experimental data for the use of energetic materials. As a promising high-energy and insensitive energetic material, LLM-105 has been investigated under extreme conditions such as high pressure and high temperature. However, little information is available about the effect of water on LLM-105 under high pressure and high temperature. In this work, the interaction between LLM-105 and water under HP-HT was investigated in detail. As a result, the dissolving behavior of LLM-105 in water under high pressure and high temperature is related to the initial pressure. When the initial pressure is less than 1 GPa, LLM-105 crystals are dissolved in high-temperature water; when the initial pressure is above 1 GPa, LLM-105 particles are only decomposed in high-temperature water. When the solution is saturated at a high temperature, recrystallization of the LLM-105 sample appears in the solution. High pressure hindered the dissolution process of the sample in HP-HT water because the interaction between the solute and the solvent was weakened by high pressure. The initial pressure is one of the significant parameters that determines whether LLM-105 crystals can be dissolved in high-temperature water. More importantly, water under high pressure and high temperature can not only act as a solvent when dissolving the samples but also act as a catalyst to accelerate the decomposition process. In addition, the HP-HT water reduced the decomposition temperature of the LLM-105 crystal to a large extent. The research in this paper not only provides insights into the interaction between LLM-105 and water but also contributes to the performance of energetic materials under extreme conditions and their practical applications in complex conditions.

Isothermal structural evolution of CL-20/HMX cocrystals under slow roasting at 190 °C.

As a new type of energetic material, cocrystal explosives demonstrate many excellent properties, such as high energy density and low sensitivity, due to the interaction between the molecules of the two components. The known decomposition temperature is 235 °C for CL-20/HMX cocrystals at a faster heating rate. CL-20 molecules could separate from the cocrystal matrix and decompose at a higher temperature, much lower than the decomposition temperature. The current work provided deep insight into the isothermal structural evolution of CL-20/HMX cocrystals with slow roasting at 190 °C. We found that the initial decomposition originates from separating CL-20 molecules from the surface along the (010) plane of the cocrystals. The gas products, such as NO2 and NO, escape from the largest exposed surface of the (010) plane and generates microbubbles and microholes. At the same time, the residual HMX molecules form δ-phase HMX crystals and shrink the volume by 72%. By increasing the time held at 190 °C, the decomposition of CL-20 molecules and recrystallization of the residual HMX molecules form a gully-like structure on the (010) plane of the CL-20/HMX cocrystal. After a long time at 190 °C, the CL-20 component completely decomposes, and all HMX molecules recrystallize in the δ-HMX form. The interaction between HMX and CL-20 molecules makes the decomposition rate of the CL-20/HMX cocrystal much slower than that of the CL-20 pure crystal with a similar decomposition activation energy during isothermal heating. This work can help to deeply understand the safety of CL-20/HMX cocrystal explosives at a temperature lower than the recognized decomposition temperature.

Structural evolution of CL-20/DNB cocrystals at high temperature: Phase transition and kinetics of thermal decomposition.

As a typical new energetic material, CL-20/DNB cocrystals have been recognized as a promising explosive owing to their excellent comprehensive performance. The thermal decomposition behavior, structural evolution and dynamic process of CL-20/DNB cocrystals under high temperature were studied by means of thermogravimetric differential heating, X-ray diffraction, Raman spectroscopy to gain insight into the cocrystal materials. The study found that the decomposition of CL-20/DNB cocrystal is a heterogeneous process accompanied by the sublimation of DNB and structural change of CL-20. The phase transition of ߠ→ Î³-CL-20 was observed at 120 °C. The kinetics of decomposition and the mechanism of micro structural evolution on CL-20/DNB cocrystals with heating were revealed. The primary NO⋯H hydrogen bonds of the cocrystal are broken, accompanied by the melting of DNB in the temperature range of 100-120 °C. Subsequently, the DNB single component decomposes completely, leading to lattice collapse of cocrystal; simultaneously, CL-20 undergoes a transition process from ß phase to γ phase. Ultimately, γ-CL-20 gradually decomposes with increasing temperature. The activation energy of cocrystal is also obtained as 129 ± 10 kJ/mol. The understanding of cocrystal explosive was deepened and the further application was promoted.

Immunomagnetic Separation Method Integrated with the Strep-Tag II System for Rapid Enrichment and Mild Release of Exosomes.

Exosomes are important participants in numerous pathophysiological processes and hold promising application value in cancer diagnosis, monitoring, and prognosis. However, the small size (40-160 nm) and high heterogeneity of exosomes make it still challenging to enrich exosomes efficiently from the complex biological fluid microenvironment, which has largely restricted their downstream analysis and clinical application. In this work, we introduced a novel method for rapid isolation and mild release of exosomes from the cell culture supernatant. A Strep-tag II-based immunomagnetic isolation (SIMI) system was constructed by modifying the capture antibodies onto magnetic nanoparticles through specific and reversible recognition between Strep-Tactin and Strep-tag II. Due to their high affinity and binding selectivity, exosomes could be isolated within 38 min with an isolation efficiency of 82.5% and a release efficiency of 62%. Compared with the gold-standard ultracentrifugation, the SIMI system could harvest nearly 59% more exosomes from the 293 T cell culture medium with shorter isolation time and higher purity. In addition, cellular uptake assay indicated that exosomes released from magnetic nanoparticles could maintain their high biological activity. These superior characteristics show that this novel method is a fast, efficient, and nondestructive exosome isolation tool and thus could potentially be further utilized in various exosome-related applications, e.g., disease diagnosis and drug delivery.

Molecular conformation evolutions of trans HNS under high pressure.

The molecular conformation evolution of Hexanitrostilbene (HNS) under high pressure was systematically investigated using Raman and Fourier transform infrared (FTIR) spectroscopy. The vibration modes of HNS associated with C-H, nitro groups, CC and the ring have been analyzed and clarified in detail under ambient conditions. trans-HNS is symmetrically distributed about -CHCH-, and six nitro groups are symmetrically distributed under ambient conditions. Two molecular conformation changes of HNS were observed at 1.4 GPa and 5 GPa due to the variations of hydrogen-bond interaction between C-H (in the ring) and N-O and the distortion of trans olefin, respectively. The hydrogen-bond interaction between C-H (in the ring) and N-O strengthened at 1.4 GPa. It induced the degenerated symmetry of the nitro groups and the Raman changes of νas (NO2), ν(CC), ν(C-C) and ν(C-H). In addition, the nonplanarity property of HNS and the sensitivity of trans olefin to pressure promoted the deformation of trans olefin, as well as the hydrogen bond interaction between C-H (in trans olefin) and N-O at about 5 GPa. When further loading pressure on HNS, the variations in the hydrogen-bond interaction between C-H and N-O restricted the vibrations of C-H, NO2 and the ring. It blocked the nonradiative pathway and activated the strong fluorescent background in the Raman spectra as the pressure increased above 5.7 GPa. These current results reveal that there is no structural transformation and only conformational changes under high pressure for HNS.

Automated quantification and statistical assessment of proliferating cardiomyocyte rates in embryonic hearts.

The use of digital image analysis and count regression models contributes to the reproducibility and rigor of histological studies in cardiovascular research. The use of formalized computer-based quantification strategies of histological images essentially removes potential researcher bias, allows for higher analysis throughput, and enables easy sharing of formalized quantification tools, contributing to research transparency, and data transferability. Moreover, the use of count regression models rather than ratios in statistical analysis of cell population data incorporates the extent of sampling into analysis and acknowledges the non-Gaussian nature of count distributions. Using quantification of proliferating cardiomyocytes in embryonic murine hearts as an example, we describe how these improvements can be implemented using open-source artificial intelligence-based image analysis tools and novel count regression models to efficiently analyze real-life data.

A sample-to-answer DNA detection microfluidic system integrating sample pretreatment and smartphone-readable gradient plasmonic photothermal continuous-flow PCR.

As the gold standard for nucleic acid detection, full-process polymerase chain reaction (PCR) analysis often falls into the dilemma of complex workflow, time-consuming, and high equipment costs. Therefore, we designed and optimized a DNA quantification microfluidic system by strategically integrating sample pretreatment and a smartphone-readable gradient plasmonic photothermal (GPPT) continuous-flow PCR (CF-PCR). Through preloading and sequential injection of immiscible extraction reagents, combined with magnetic bead (MB) manipulation, the microfluidic chip successfully purified and concentrated 100 µL of HBV-DNA spiked plasma into a 20-µL purified sample within 14 minutes. With a digital PCR platform, the optimized experiments showed that the DNA extraction efficiency can reach 69% at an immiscible reagent configuration ratio of 10 : 10 : 1 : 12 : 2 (sample : lysis/binding buffer : MB : silicone oil : eluent) and a flow rate of 25 µL min-1. For the first time, we used gold nanorod (AuNR)-doped PDMS to prepare a CF-PCR submodule for the amplification of a 40 µL PCR mixture. Due to the plasmonic photothermal effect of AuNRs and the gradient intensity of an expanded laser spot, the PCR thermal gradient was formed on a coin-sized area. The compact annular thermal-microfluidic layout, optimized DNA dye concentration, and chip transmittance synergistically enable a rarely reported smartphone-based fluorescence CF-PCR, greatly simplifying thermal control and detection setup. Prototype construction and validation experiments show that the microsystem can complete the sample-to-answer quantification of HBV-DNA with a dynamic linear range from 1.2 × 101 to 1.2 × 106 copies per µL in ∼37 minutes. This novel microfluidic solution effectively bridges the technical gap between the CF-PCR, sample pretreatment and result characterization, making the workflow standardized and rapid and requiring <15% of the commercial instrument cost. The simplicity, rapidity and low cost of this work make it promising for applications in decentralized laboratories and low-resource settings.

Orthorhombic-to-Hexagonal Phase Transition of REF3 (RE = Sm to Lu and Y) under High Pressure.

For the famous functional REF3 family, there exist two typical structures, that is, orthorhombic phase and hexagonal phase. In the present work, high pressure behaviors of the orthorhombic phase REF3 (RE = Sm to Lu and Y) were investigated by experimental methods and first-principles calculations. The pressure-induced phase transitions of GdF3, TbF3, YbF3, and LuF3 were studied by using in situ photoluminescence measurements in the diamond anvil cell. At room temperature, all these four compounds follow the phase transition route from orthorhombic to hexagonal phase at 5.5-20.6 GPa. The pressure ranges of phase transition are 5.5-9.3, 8.4-11.9, 13.5-20.3, and 14.8-20.6 GPa for GdF3, TbF3, YbF3, and LuF3, respectively. In combination with first-principles calculations, we infer that all orthorhombic REF3 members from Sm-Lu and Y obey the same orthorhombic-to-hexagonal phase transition rules under high pressures. For lanthanide trifluorides, the transition pressures increase as zero pressure volumes of REF3 in the orthorhombic phase become smaller. As the calculation results show, this is because the difference in value of energy from the two structures is larger. This work not only provides precise structural change but also benefits the understanding of two typical structures for rare-earth trifluorides, which may play a significant role in the applications of REF3.

Pressure-Induced Indirect-Direct Bandgap Transition of CsPbBr3 Single Crystal and Its Effect on Photoluminescence Quantum Yield.

Despite extensive study, the bandgap characteristics of lead halide perovskites are not well understood. Usually, these materials are considered as direct bandgap semiconductors, while their photoluminescence quantum yield (PLQY) is very low in the solid state or single crystal (SC) state. Some researchers have noted a weak indirect bandgap below the direct bandgap transition in these perovskites. Herein, application of pressure to a CsPbBr3 SC and first-principles calculations reveal that the nature of the bandgap becomes more direct at a relatively low pressure due to decreased dynamic Rashba splitting. This effect results in a dramatic PLQY improvement, improved more than 90 times, which overturns the traditional concept that the PLQY of lead halide perovskite SC cannot exceed 10%. Application of higher pressure transformed the CsPbBr3 SC into a pure indirect bandgap phase, which can be maintained at near-ambient pressure. It is thus proved that lead halide perovskites can induce a phase transition between direct and indirect bandgaps. In addition, distinct piezochromism is observed for a perovskite SC for the first time. This work provides a novel framework to understand the optoelectronic properties of these important materials.

Inference of a "Hot Ice" Layer in Nitrogen-Rich Planets: Demixing the Phase Diagram and Phase Composition for Variable Concentration Helium-Nitrogen Mixtures Based on Isothermal Compression.

Van der Waals (vdW) chemistry in simple molecular systems may be important for understanding the structure and properties of the interiors of the outer planets and their satellites, where pressures are high and such components may be abundant. In the current study, Raman spectra and visual observation are employed to investigate the phase separation and composition determination for helium-nitrogen mixtures with helium concentrations from 20 to 95% along the 295 K isothermal compression. Fluid-fluid-solid triple-phase equilibrium and several equilibria of two phases including fluid-fluid and fluid-solid have been observed in different helium-nitrogen mixtures upon loading or unloading pressure. The homogeneous fluid in helium-nitrogen mixtures separates into a helium-rich fluid (F1) and a nitrogen-rich fluid (F2) with increasing pressure. The triple-phase point occurs at 295 K and 8.8 GPa for a solid-phase (N2)11He vdW compound, fluid F1 with around 50% helium, and fluid F2 with 95% helium. Helium concentrations of F1 coexisted with the (N2)11He vdW compound or δ-N2 in helium-nitrogen mixtures with different helium concentrations between 40 and 50% and between 20 and 40%, respectively. In addition, the helium concentration of F2 is the same in helium-nitrogen mixtures with different helium concentrations and decreases upon loading pressure. Pressure-induced nitrogen molecule ordering at 32.6 GPa and a structural phase transition at 110 GPa are observed in (N2)11He. In addition, at 187 GPa, a pressure-induced transition to an amorphous state is identified.

Multiple yet switchable hydrogen-bonded organic frameworks with white-light emission.

The development of new strategies to construct on-demand porous lattice frameworks from simple motifs is desirable. However, mitigating complexity while combing multiplicity and reversibility in the porous architectures is a challenging task. Herein, based on the synergy of dynamic intermolecular interactions and flexible molecular conformation of a simple cyano-modified tetraphenylethylene tecton, eleven kinetic-stable hydrogen-bonded organic frameworks (HOFs) with various shapes and two thermo-stable non-porous structures with rare perpendicular conformation are obtained. Multimode reversible structural transformations along with visible fluorescence output between porous and non-porous or between different porous forms is realized under different external stimuli. Furthermore, the collaborative of flexible framework and soft long-chain guests facilitate the relaxation from intrinsic blue emission to yellow emission in the excited state, which represents a strategy for generating white-light emission. The dynamic intermolecular interactions, facilitated by flexible molecular conformation and soft guests, diversifies the strategies of construction of versatile smart molecular frameworks.

A one-pot CRISPR/Cas13a-based contamination-free biosensor for low-cost and rapid nucleic acid diagnostics.

The pandemic due to the outbreak of 2019 coronavirus disease (COVID-19) caused by novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has raised significant public health concerns. Rapid, affordable, and accurate diagnostic testing not only paves the way for the effective treatment of diseases, but also plays a crucial role in preventing the spreading of infectious diseases. Herein, a one-pot CRISPR/Cas13a-based visual biosensor was proposed and developed for the rapid and low-cost nucleic acid detection. By combining Cas13a cleavage and Recombinase Polymerase Amplification (RPA) in a one-pot reaction in a disposable tube-in-tube vessel, amplicon contamination could be completely avoided. The RPA reaction is carried out in the inner tube containing two hydrophobic holes at the bottom. After the completion of amplification reaction, the reaction solution enters the outer tube containing pre-stored Cas13a reagent under the action of centrifugation or shaking. Inner and outer tubes are combined to form an independent reaction pot to complete the nucleic acid detection without opening the lid. This newly developed nucleic acid detection method not only meets the need of rapid nucleic acid detection at home without the need for any specialized equipment, but also fulfils the requirement of rapid on-site nucleic acid detection with the aid of small automated instruments. In this study, CRISPR/Cas13a and CRISPR/Cas12a were used to verify the reliability of the developed one-pot nucleic acid detection method. The performance of the system was verified by detecting the DNA virus, i.e., African swine fever virus (ASFV) and the RNA virus, i.e., SARS-Cov-2. The results indicate that the proposed method possesses a limit of detection of 3 copy/µL. The negative and positive test results are consistent with the results of real-time fluorescence quantitative polymerase chain reaction (PCR), but the time required is shorter and the cost is lower. Thus, this study makes this method available in resource-limited areas for the purpose of large-scale screening and in case of epidemic outbreak.

Pressure effects on the thermal decomposition of the LLM-105 crystal.

Thermal mechanical responses under high temperature and high pressure are basic information to understand the performance of energetic materials. In this work, the pressure effects on the thermal decay of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) are explored. Up to the initial pressure of 4.6 GPa, the pressure dependent decomposition boundary is built and no phase transition occurs until the decomposition of the LLM-105 crystal. The decomposition temperature is significantly lifted via a weak loading pressure. The experimental measurement confirms the decomposition products, including NO2, CO2 and NH3, which are predicted by the density functional tight-binding molecular dynamics method. The calculation described the details of thermal decay in the initial stages under high pressure. The sudden drop in the shifts of the Raman modes associated with hydrogen bonds under high pressure indicates the strengthening of the intermolecular hydrogen bonds and the occurrence of intermolecular hydrogen transfer prior to crystal decomposition. The simulation supported the existence of intermolecular hydrogen transfer and provided the transfer path and decomposition mechanism. All of these jobs not only contribute significantly to the understanding of thermal decomposition of energetic materials as a function of pressure, but also contribute to the understanding of sensitivity mechanisms and safety issues.

PRDM16 Is a Compact Myocardium-Enriched Transcription Factor Required to Maintain Compact Myocardial Cardiomyocyte Identity in Left Ventricle.

BACKGROUND: Left ventricular noncompaction cardiomyopathy (LVNC) was discovered half a century ago as a cardiomyopathy with excessive trabeculation and a thin ventricular wall. In the decades since, numerous studies have demonstrated that LVNC primarily has an effect on left ventricles (LVs) and is often associated with LV dilation and dysfunction. However, in part because of the lack of suitable mouse models that faithfully mirror the selective LV vulnerability in patients, mechanisms underlying the susceptibility of LVs to dilation and dysfunction in LVNC remain unknown. Genetic studies have revealed that deletions and mutations in PRDM16 (PR domain-containing 16) cause LVNC, but previous conditional Prdm16 knockout mouse models do not mirror the LVNC phenotype in patients, and the underlying molecular mechanisms by which PRDM16 deficiency causes LVNC are still unclear. METHODS: Prdm16 cardiomyocyte-specific knockout (Prdm16cKO) mice were generated and analyzed for cardiac phenotypes. RNA sequencing and chromatin immunoprecipitation deep sequencing were performed to identify direct transcriptional targets of PRDM16 in cardiomyocytes. Single-cell RNA sequencing in combination with spatial transcriptomics was used to determine cardiomyocyte identity at the single-cell level. RESULTS: Cardiomyocyte-specific ablation of Prdm16 in mice caused LV-specific dilation and dysfunction, as well as biventricular noncompaction, which fully recapitulated LVNC in patients. PRDM16 functioned mechanistically as a compact myocardium-enriched transcription factor that activated compact myocardial genes while repressing trabecular myocardial genes in LV compact myocardium. Consequently, Prdm16cKO LV compact myocardial cardiomyocytes shifted from their normal transcriptomic identity to a transcriptional signature resembling trabecular myocardial cardiomyocytes or neurons. Chamber-specific transcriptional regulation by PRDM16 was attributable in part to its cooperation with LV-enriched transcription factors Tbx5 and Hand1. CONCLUSIONS: These results demonstrate that disruption of proper specification of compact cardiomyocytes may play a key role in the pathogenesis of LVNC. They also shed light on underlying mechanisms of the LV-restricted transcriptional program governing LV chamber growth and maturation, providing a tangible explanation for the susceptibility of LV in a subset of LVNC cardiomyopathies.

Fast-Response Metal-Semiconductor-Metal Junction Ultraviolet Photodetector Based on ZnS:Mn Nanorod Networks via a Cost-Effective Method.

In this work, Mn2+-doped ZnS nanorods were synthesized by a facile hydrothermal method. The morphology, structure, and composition of the as-prepared samples were investigated. The temperature-dependent photoluminescence of ZnS:Mn nanorods was analyzed, and the corresponding activation energies were calculated by using a simple two-step rate equation. Mn2+-related orange emission (4T1 → 6A1) demonstrates high stability and is comparatively less affected by the temperature variations than the defect-related emission. A metal-semiconductor-metal junction ultraviolet photodetector based on the nanorod networks has been fabricated by a cost-effective method. The device exhibits visible blindness, superior ultraviolet photodetection with a responsivity of 1.62 A/W, and significantly fast photodetection response with the rise and decay times of 12 and 25 ms, respectively.

Possible Topological Hall Effect above Room Temperature in Layered Cr1.2Te2 Ferromagnet.

Topological Hall effect (THE) has been used as a powerful tool to unlock spin chirality in novel magnetic materials. Recent focus has been widely paid to THE and possible chiral spin textures in two-dimensional (2D) layered magnetic materials. However, the room-temperature THE has been barely reported in 2D materials, which hinders its practical applications in 2D spintronics. In this paper, we report a possible THE signal featuring antisymmetric peaks in a wide temperature window up to 320 K in Cr1.2Te2, a new quasi-2D ferromagnetic material. The temperature, thickness, and magnetic field dependences of the THE lead to potential spin chirality origin that is associated with the spin canting under external magnetic fields. Our work holds promise for practical applications in future chiral spin-based vdW spintronic devices.

Colossal Anomalous Hall Effect in Ferromagnetic van der Waals CrTe2.

van der Waals crystals exhibit excellent material performance when exfoliated to few-atomic-layer thickness. In contrast, the van der Waals thin films more than 10 nm thick are believed to show bulk properties, in which outstanding material performance is rarely found. Here we report the largest anomalous Hall conductivity observed so far in a 170 nm van der Waals ferromagnetic 1T-CrTe2 flake, which reaches 67,000 Ω-1 cm-1. Such a colossal anomalous Hall conductivity in 1T-CrTe2 is dominated by the extrinsic skew scattering process rather than the intrinsic Berry phase effect, as evidenced by the linear relation between the anomalous Hall conductivity and the longitudinal conductivity. Defying the dilemma of mutually exclusive large anomalous Hall angle and high electric conductivity for most ferromagnets, 1T-CrTe2 achieves both in a thin film sample. Considering the shared physics of the anomalous Hall effect and the spin Hall effect, our finding offers a guideline for searching large spin Hall materials of high conductivity which may overcome the bottleneck of overheating in spintronics devices.