Comprehensive analysis of environmental exposure to hazardous trace elements and lung function: a national cross-sectional study.

BACKGROUND: There is growing interest in the joint effects of hazardous trace elements (HTEs) on lung function deficits, but the data are limited. This is a critical research gap given increased global industrialisation. METHODS: A national cross-sectional study including spirometry was performed among 2112 adults across 11 provinces in China between 2020 and 2021. A total of 27 HTEs were quantified from urine samples. Generalised linear models and quantile-based g-computation were used to explore the individual and joint effects of urinary HTEs on lung function, respectively. RESULTS: Overall, there were negative associations between forced expiratory volume in 1 s (FEV1) and urinary arsenic (As) (z-score coefficient, -0.150; 95% CI, -0.262 to -0.038 per 1 ln-unit increase), barium (Ba) (-0.148, 95% CI: -0.258 to -0.039), cadmium (Cd) (-0.132, 95% CI: -0.236 to -0.028), thallium (Tl) (-0.137, 95% CI: -0.257 to -0.018), strontium (Sr) (-0.147, 95% CI: -0.273 to -0.022) and lead (Pb) (-0.121, 95% CI: -0.219 to -0.023). Similar results were observed for forced vital capacity (FVC) with urinary As, Ba and Pb and FEV1/FVC with titanium (Ti), As, Sr, Cd, Tl and Pb. We found borderline associations between the ln-quartile of joint HTEs and decreased FEV1 (-20 mL, 95% CI: -48 to +8) and FVC (-14 mL, 95% CI: -49 to+2). Ba and Ti were assigned the largest negative weights for FEV1 and FVC within the model, respectively. CONCLUSION: Our study investigating a wide range of HTEs in a highly polluted setting suggests that higher urinary HTE concentrations are associated with lower lung function, especially for emerging Ti and Ba, which need to be monitored or regulated to improve lung health.

Hepatic injury and ileitis associated with gut microbiota dysbiosis in mice upon F-53B exposure.

Chlorinated polyfluorinated ether sulfonate (F-53B), a substitute of perfluorooctane sulfonic acid (PFOS), has attracted significant attention for its link to hepatotoxicity and enterotoxicity. Nevertheless, the underlying mechanisms of F-53B-induced enterohepatic toxicity remain incompletely understood. This study aimed to explore the role of F-53B exposure on enterohepatic injury based on the gut microbiota, pathological and molecular analysis in mice. Here, we exposed C57BL/6 mice to F-53B (0, 4, 40, and 400 µg/L) for 28 days. Our findings revealed a significant accumulation of F-53B in the liver, followed by small intestines, and feces. In addition, F-53B induced pathological collagen fiber deposition and lipoid degeneration, up-regulated the expression of fatty acid ß-oxidation-related genes (PPARα and PPARγ, etc), while simultaneously down-regulating pro-inflammatory genes (Nlrp3, IL-1ß, and Mcp1) in the liver. Meanwhile, F-53B induced ileal mucosal barrier damage, and an up-regulation of pro-inflammatory genes and mucosal barrier-related genes (Muc1, Muc2, Claudin1, Occludin, Mct1, and ZO-1) in the ileum. Importantly, F-53B distinctly altered gut microbiota compositions by increasing the abundance of Akkermansia and decreasing the abundance of Prevotellaceae_NK3B31_group in the feces. F-53B-altered microbiota compositions were significantly associated with genes related to fatty acid ß-oxidation, inflammation, and mucosal barrier. In summary, our results demonstrate that F-53B is capable of inducing hepatic injury, ileitis, and gut microbiota dysbiosis in mice, and the gut microbiota dysbiosis may play an important role in the F-53B-induced enterohepatic toxicity.

Associations of prenatal exposure to perfluoroalkyl substances with preterm birth: A family-based birth cohort study.

Studies have investigated associations between maternal exposure to PFAS and preterm birth, but the impact of paternal and overall family exposure to PFAS mixtures on preterm birth remains unknown. To address this knowledge gap, a total of 355 preterm births and 481 controls were selected for a family-based birth cohort study in a coastal area of China, between 2016 and 2018. Seven PFAS, including perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA), were quantified in maternal, paternal and neonatal sera. Preterm birth was defined as live delivery at <37 completed gestational weeks. Bayesian kernel machine regression (BKMR) model was used to inspect the combined effect of family PFAS mixtures. Latent class analysis was used to identify family-level PFAS exposure profiles. Multiple linear regression analysis showed higher odds of preterm birth in association with higher maternal PFBA (OR = 1.16, 95%CI:1.09, 1.25), PFOA (OR = 1.51, 95%CI:1.27, 1.80), PFOS (OR = 2.07, 95%CI:1.70, 2.52) and PFNA (OR = 1.36, 95%CI: 1.01, 1.83), and neonatal PFBA (OR = 1.16, 95%CI:1.05,1.29), PFHxA (OR = 1.46, 95%CI:1.32, 1.62), PFHxS (OR = 1.15, 95%CI:1.05, 1.26) and PFNA (OR = 1.30, 95%CI:1.09,1.56). The associations were reversed between individual paternal PFAS exposures and preterm birth. At the family level, higher PFAS mixture concentration was associated with higher odds of preterm birth. In particular, higher PFNA and PFDA exposure was associated with greater preterm birth risk (OR = 2.55, 95%CI:1.45, 4.50). The PFAS-preterm association was modified by family-level seafood consumption. Our results suggest that higher family-level PFNA and PFDA exposure was associated with greater preterm birth risk, although the results for individual paternal, maternal and neonatal PFAS exposures were contradictory. If replicated in other coastal areas, these findings highlight a need to focus on the family triad and to consider seafood consumption when assessing the reproductive toxicity of PFAS exposure.

SnS2 /Co3 S4 Hollow Nanocubes Anchored on S-Doped Graphene for Ultrafast and Stable Na-Ion Storage.

SnS2 has been widely studied as an anode material for sodium-ion batteries (SIBs) based on the high theoretical capacity and layered structure. Unfortunately, rapid capacity decay associated with volume variation during cycling limits practical application. Herein, SnS2 /Co3 S4 hollow nanocubes anchored on S-doped graphene are synthesized for the first time via coprecipitation and hydrothermal methods. When applied as the anode for SIBs, the sample delivers a distinguished charge specific capacity of 1141.8 mAh g-1 and there is no significant capacity decay (0.1 A g-1 for 50 cycles). When the rate is increased to 0.5 A g-1 , it presents 845.7 mAh g-1 after cycling 100 times. Furthermore, the composite also exhibits an ultrafast sodium storage capability where 392.9 mAh g-1 can be obtained at 10 A g-1 and the charging time is less than 3 min. The outstanding electrochemical properties can be ascribed to the enhancement of conductivity for the addition of S-doped graphene and the existence of p-n junctions in the SnS2 /Co3 S4 heterostructure. Moreover, the presence of mesopores between nanosheets can alleviate volume expansion during cycling as well as being beneficial for the migration of Na+ .

Ferroelectrically tunable magnetic skyrmions in ultrathin oxide heterostructures.

Magnetic skyrmions are topologically protected whirling spin texture. Their nanoscale dimensions, topologically protected stability and solitonic nature, together are promising for future spintronics applications. To translate these compelling features into practical spintronic devices, a key challenge lies in achieving effective control of skyrmion properties, such as size, density and thermodynamic stability. Here, we report the discovery of ferroelectrically tunable skyrmions in ultrathin BaTiO3/SrRuO3 bilayer heterostructures. The ferroelectric proximity effect at the BaTiO3/SrRuO3 heterointerface triggers a sizeable Dzyaloshinskii-Moriya interaction, thus stabilizing robust skyrmions with diameters less than a hundred nanometres. Moreover, by manipulating the ferroelectric polarization of the BaTiO3 layer, we achieve local, switchable and nonvolatile control of both skyrmion density and thermodynamic stability. This ferroelectrically tunable skyrmion system can simultaneously enhance the integratability and addressability of skyrmion-based functional devices.

Failure of Lithium-Ion Batteries Accelerated by Gravity.

The safety concerns surrounding lithium-ion batteries (LIBs) have garnered increasing attention due to their potential to endanger lives and incur significant financial losses. However, the origins of battery failures are diverse, presenting significant challenges in developing safety measures to mitigate accidental catastrophes. In this study, the aging mechanism of LiNi0.5Co0.2Mn0.3O2||graphite-based cylindrical 18,650 LIBs stored at room temperature for two years was investigated. It was found that an uneven distribution of electrolytes can be caused by gravity, leading to temperature variations within the battery. Specifically, it was observed that the temperature at the top of the battery was approximately -0.89 °C higher than at the bottom, correlating with an increase in partial internal resistance. Additionally, upon disassembly and analysis of spent batteries, the most significant damage to electrode materials at the top of the battery was observed. These findings suggest that gravity-induced electrolyte insufficiency exacerbates side reactions, particularly at the top of the battery. This study offers a unique perspective on the safety concerns associated with high-energy-density batteries in long-term and large-scale applications.

Surface Reconstruction of High-Voltage LiNi0.5Mn1.5O4 Cathode via the Sculpture Method toward Enhanced Stability.

High-voltage LiNi0.5Mn1.5O4 (LNMO) cathodes suffer from severe capacity degradation during long-term cycling due the manganese dissolution and their high operating voltage (∼4.95 V), which pose serious challenges at the surface or interface. Moreover, both traditional ion-doping and passivation layer coating are difficult to apply consistently to LNMO cathode because of their complicated procedures, especially in large-scale production. To address these issues, a strategy employing HNO3/H2O2 leaching in synergy with a sintering process at a mid-temperature of 700 °C was used to achieve selective surface reconstruction. An optimal ratio of reactants was applied to balance the capacity and the cyclic stability of the LNMO cathode. The optimized valence composition of Mn on the material surface mitigates the occurrence of Jahn-Teller distortion, accompanied by a reasonable ratio of ordered and disordered phases and the concentration of oxygen vacancies after sintering, which improves the interface behavior between the electrode and electrolyte. This method delivers a high reversible capacity of 116.5 mAh g-1 after 200 cycles at 0.5 C (1 C = 147 mAh g-1) with a capacity retention of 91.30% and 110 mAh g-1 with a remarkably high capacity retention of 86.85% after 500 cycles at 2 C. This balanced approach, utilizing the protective effects of oxidation (O22-) and the erosive action of acid (H+), is proposed to achieve regional surface reconstruction of advanced LNMO cathode. This opens up a strategy for improving oxide-based cathode materials with low cost and mass production capability, especially favoring high consistency.

A rigid and compact piezoelectric motor with high output efficiency.

We introduce a novel piezoelectric stepper motor featuring high compactness, rigidity, and any direction operability. Here, not only is the structure of high novelty but also the working principle very simple. The piezo stacks unit is sandwiched between two spring finger pieces, with almost equal clamping forces applied between the top of the piezo stacks' unit and the spring finger piece. Applying individual driving signals to each of the five piezo stack pairs, causing deformation one by one in the same direction, followed by simultaneous recovery in the reverse direction, enables movement of the frame part. The optimized clamping force of the piezoelectric stack units and spring fingers ensures maximum output force. The motor's operational capability at low threshold voltages, specifically 8 V for downward movement and 10 V for upward movement, confirmed its efficacy in both vertical and horizontal directions. The motor's operational capability at a low threshold voltage of 10 V confirmed its efficacy in both vertical and horizontal directions. At room temperature, step size ranges from 0.3 to 7.4 µm at 20 Hz frequency and varying driving voltage from 10 to 180 V. It has a maximum travel range of about 5 mm and can lift a maximum load of 220 g in an upward direction, so the maximum output force generated by this motor is 2.2 N. The compact and rigid design is capable of building an atomically resolved scanning probe microscope, and its working ability has the potential to use the cleavage of different types of samples in limited space environments, such as the small-bore superconducting magnet and low temperature.

A novel STM for quality atomic resolution with piezoelectric motor of high compactness and simplicity.

Scanning tunneling microscope (STM) is a renowned scientific tool for obtaining high-resolution atomic images of materials. Herein, we present an innovative design of the scanning unit with a compact yet powerful inertial piezoelectric motor inspired by the Spider Drive motor principle. The scanning unit mainly consists of a small 9 mm long piezoelectric tube scanner (PTS), one end of which is coaxially connected to the main sapphire body of the STM. Of particular emphasis in this design is the piezoelectric shaft (PS), constructed from piezoelectric material instead of conventional metallic or zirconium materials. The PS is a rectangular piezoelectric stack composed of two piezoelectric plates, which are elastically clamped on the inner wall of the PTS via a spring strip. The PTS and PS expand and contract independently with each other to improve the inertial force and reduce the threshold voltage. To ensure the stability of the PS and balance the stepping performance of the inertial motor, a counterweight, and a matching conical spring are fixed at the tail of the PS. This innovative design allows for the assessment of scanning unit performance by applying a driving signal, threshold voltage is 50 V at room temperature. Step sizes vary from 0.1 to 1 µm by changing the driving signal at room temperature. Furthermore, we successfully obtained atomic-resolution images of a highly oriented pyrolytic graphite (HOPG) sample and low drift rates of 23.4 pm/min and 34.6 pm/min in X-Y plane and Z direction, respectively, under ambient conditions. This small, compact STM unit has the potential for the development of a rotatable STM for use in cryogen-free magnets, and superconducting magnets.

Isolated scan unit and scanning tunneling microscope for stable imaging in ultra-high magnetic fields.

The high resolution of a scanning tunneling microscope (STM) relies on the stability of its scan unit. In this study, we present an isolated scan unit featuring non-magnetic design and ultra-high stability, as well as bidirectional movement capability. Different types of piezoelectric motors can be incorporated into the scan unit to create a highly stable STM. The standalone structure of scan unit ensures a stable atomic imaging process by decreasing noise generated by motor. The non-magnetic design makes the scan unit work stable in high magnetic field conditions. Moreover, we have successfully constructed a novel STM based on the isolated scan unit, in which two inertial piezoelectric motors act as the coarse approach actuators. The exceptional performance of homebuilt STM is proved by the high-resolution atomic images and dI/dV spectrums on NbSe2 surface at varying temperatures, as well as the raw-data images of graphite obtained at ultra-high magnetic fields of 23 T. According to the literature research, no STM has previously reported the atomic image at extreme conditions of 2 K low temperature and 23 T ultra-high magnetic field. Additionally, we present the ultra-low drift rates between the tip and sample at varying temperatures, as well as when raising the magnetic fields from 0 T to 23 T, indicating the ultra-high stability of the STM in high magnetic field conditions. The outstanding performance of our stable STM hold great potential for investigating the materials in ultra-high magnetic fields.

An ultracompact scanning tunneling microscope within a Φ 10 piezo tube in a 20 T superconducting magnet.

Low-temperature scanning tunneling microscopy and spectroscopy (STM/S) help to better understand the fundamental physics of condensed matter. We present an ultracompact STM within a Φ 10 piezo tube in a 20 T superconducting magnet. The carefully cut piezo tube contains the STM's coarse-positioning assembly. Loading an STM tip-sample mechanical loop into the piezo tube with special cut openings enables an ultracompact pencil-size dimension down to Φ 10 mm, in which fine-machined nonmagnetic parts are assembled to enable slide-stick motion and xyz-scanning procedures. The small size leads to a higher resonant frequency, a typical feature of a rigid STM instrument, increasing its vibration immunity. Scanning by moving the sample while keeping the tip stationary improves the stability of the tip-sample junction compared to moving the tip. Taking advantage of its high-field compatibility and rigid design, our STM captures the atomically resolved topography of highly oriented pyrolytic graphite (HOPG) at 1.5 K and in magnetic fields up to 17 T. The topography of graphene lattice and graphite is simultaneously recorded on an atomic terrace of HOPG, unveiling a modified local charge density at a surface defect. The superconducting energy gaps of layered type-II superconductors NbSe2 and PdBi2 are well resolved through dI/dV tunneling spectra at sub-2 K. Our unique STM is highly suitable for potential STM/S applications in world-class high-field facilities where the strong magnetic field can exceed 30 T.

Glovebox-assisted magnetic force microscope for studying air-sensitive samples in a cryogen-free magnet.

Most known two-dimensional magnets exhibit a high sensitivity to air, making direct characterization of their domain textures technically challenging. Herein, we report on the construction and performance of a glovebox-assisted magnetic force microscope (MFM) operating in a cryogen-free magnet, realizing imaging of the intrinsic magnetic structure of water and oxygen-sensitive materials. It features a compact tubular probe for a 50 mm-diameter variable temperature insert installed in a 12 T cryogen-free magnet. A detachable sealing chamber can be electrically connected to the tail of the probe, and its pump port can be opened and closed by a vacuum manipulator located on the top of the probe. This sealing chamber enables sample loading and positioning in the glove box and MFM transfer to the magnet maintained in an inert gas atmosphere (in this case, argon and helium gas). The performance of the MFM is demonstrated by directly imaging the surface (using no buffer layer, such as h-BN) of very air-sensitive van der Waals magnetic material chromium triiodide (CrI3) samples at low temperatures as low as 5 K and high magnetic fields up to 11.9 T. The system's adaptability permits replacing the MFM unit with a scanning tunneling microscope unit, enabling high-resolution atomic imaging of air-sensitive surface samples.

Real-Space Imaging of Intrinsic Symmetry-Breaking Spin Textures in a Kagome Lattice.

The electronic orders in kagome materials have emerged as a fertile platform for studying exotic quantum states, and their intertwining with the unique kagome lattice geometry remains elusive. While various unconventional charge orders with broken symmetry is observed, the influence of kagome symmetry on magnetic order has so far not been directly observed. Here, using a high-resolution magnetic force microscopy, it is, for the first time, observed a new lattice form of noncollinear spin textures in the kagome ferromagnet in zero magnetic field. Under the influence of the sixfold rotational symmetry of the kagome lattice, the spin textures are hexagonal in shape and can further form a honeycomb lattice structure. Subsequent thermal cycling measurements reveal that these spin textures transform into a non-uniform in-plane ferromagnetic ground state at low temperatures and can fully rebuild at elevated temperatures, showing a strong second-order phase transition feature. Moreover, some out-of-plane magnetic moments persist at low temperatures, supporting the Kane-Mele scenario in explaining the emergence of the Dirac gap. The observations establish that the electronic properties, including both charge and spin orders, are strongly coupled with the kagome lattices.

Atomic imaging with a 12 T magnetic field perpendicular or parallel to the sample surface by an ultra-stable scanning tunneling microscope.

We present the first nonmetallic scanning tunneling microscope (STM) featuring an ultra-stable tip-sample mechanical loop and capable of atomic-resolution imaging within a 12 T magnetic field that could be either perpendicular or parallel to the sample surface. This is also the first STM with an ultra-stable tip-sample mechanical loop but without a standalone scanner. The STM head is constructed only with two parts: an improved spider-drive motor and a zirconia tip holder. The motor performs both the coarse approach and atomic imaging. A supporting spring is set at the fixed end of the motor tube to decrease the tip-sample mechanical loop. The zirconia tip holder performs as the frame of the whole STM head. With the novel design, the STM head in three dimensions can be as small as 7.9 mm × 7.9 mm × 26.5 mm. The device's excellent performance is demonstrated by atomic-resolution images of graphite and NbSe2 obtained at 300 K and 2 K, as well as the high-resolution dI/dV spectrums of NbSe2 at variable temperatures. Low drift rates in the X-Y plane and Z direction further prove the imaging stability of our new STM. High-quality imaging of the Charge Density Wave (CDW) structure on a TaS2 surface shows the STM's good application capability. Continuous atomic images obtained in magnetic fields rangs from 0 T to 12 T with the direction of the magnetic field perpendicular or parallel to the sample surface show the STM's good immunity to high magnetic fields. Our results illustrate the new STM's broad application ability in extreme conditions of low temperature and high magnetic field.

Positioning and atomic imaging of micron-size graphene sheets by a scanning tunneling microscope.

We present a mechanism for directly positioning the tip over a micron-size sample by tracking the trajectory of the tip and tip shadow. A bilayer graphene sheet identified by Raman spectroscopy with a lateral size of 20 µm × 50 µm was transferred on the surface of shaped gold electrodes, on which it will be rapidly captured by a homebuilt scanning tunneling microscopy (STM) with the help of an optical microscope. Using the improved line-based imaging mode, atomic-resolution images featuring a hexagonal lattice structure on the bilayer graphene sheet were obtained by our positioning-capable STM. We have also observed a unique O-ring superstructure on graphene surface that caused by the collective interference near the boundaries or defects. Furthermore, we successfully captured a graphene sheet of size as small as 1.3 nm by a rapid and large-area searching operation; this is the first time that such a small graphene sheet has been observed with atomic resolution. The STM images of a micron-size graphene sheet illustrate the significant positioning ability and imaging precision of our homebuilt STM. Our results contribute to further STM studies on samples with ultra-small size.

Atomic-Resolution Imaging of Micron-Sized Samples Realized by High Magnetic Field Scanning Tunneling Microscopy.

Scanning tunneling microscopy (STM) can image material surfaces with atomic resolution, making it a useful tool in the areas of physics and materials. Many materials are synthesized at micron size, especially few-layer materials. Limited by their complex structure, very few STMs are capable of directly positioning and imaging a micron-sized sample with atomic resolution. Traditional STMs are designed to study the material behavior induced by temperature variation, while the physical properties induced by magnetic fields are rarely studied. In this paper, we present the design and construction of an atomic-resolution STM that can operate in a 9 T high magnetic field. More importantly, the homebuilt STM is capable of imaging micron-sized samples. The performance of the STM is demonstrated by high-quality atomic images obtained on a graphite surface, with low drift rates in the X-Y plane and Z direction. The atomic-resolution image obtained on a 32-µm graphite flake illustrates the new STM's ability of positioning and imaging micron-sized samples. Finally, we present atomic resolution images at a magnetic field range from 0 T to 9 T. The above advantages make our STM a promising tool for investigating the quantum hall effect of micron-sized layered materials.

A Novel Atomically Resolved Scanning Tunneling Microscope Capable of Working in Cryogen-Free Superconducting Magnet.

We present a novel homebuilt scanning tunneling microscope (STM) with atomic resolution integrated into a cryogen-free superconducting magnet system with a variable temperature insert. The STM head is designed as a nested structure of double piezoelectric tubes (PTs), which are connected coaxially through a sapphire frame whose top has a sample stage. A single shaft made of tantalum, with the STM tip on top, is held firmly by a spring strip inside the internal PT. The external PT drives the shaft to the tip-sample junction based on the SpiderDrive principle, and the internal PT completes the subsequent scanning and imaging work. The STM head is simple, compact, and easy to assemble. The excellent performance of the device was demonstrated by obtaining atomic-resolution images of graphite and low drift rates of 30.2 pm/min and 41.4 pm/min in the X-Y plane and Z direction, respectively, at 300K. In addition, we cooled the sample to 1.6 K and took atomic-resolution images of graphite and NbSe2. Finally, we performed a magnetic field sweep test from 0 T to 9 T at 70 K, obtaining distinct graphite images with atomic resolution under varying magnetic fields. These experiments show our newly developed STM's high stability, vibration resistance, and immunity to high magnetic fields.

Atomically resolved low-temperature scanning tunneling microscope operating in a 22 T water-cooled magnet.

We present the design and construction of a nonmetallic tip-sample mechanical loop featured Scanning Tunneling Microscope (STM) that operates in a 22 T water-cooled magnet at a low temperature of l.8 K. The STM head mainly consists of a spider-drive motor, stand-alone scanner, moveable sapphire sample holder, and sapphire frame. All parts exist in the tip-sample mechanical loop are made of sapphire to reduce the interference from high magnetic fields. Except for the necessary movement of the tip and scanner, all STM parts are stationary. More importantly, the tip-sample mechanical loop is separate from the motor after detecting the tunneling current, which helps prevent the high voltage signal interference from entering the tip-sample junction, leading to a high stable imaging. A Janis liquid helium cryostat is used to obtain a variable temperature range from 1.8 K to 300 K, and the STM head is cooled down via helium exchange gas. The STM head hangs at the bottom of a probe with a two-stage spring suspension to prevent the huge vibration generated by the water-cooled magnet from entering the tip-sample junction. The performance is demonstrated by atomically resolved STM images of graphite surface at 0 T and 22.8 T under room temperature. Furthermore, the obtained atomic-resolution images of NbSe2 at 1.8 K and 22 T, as well as high-resolution dI/dV spectrums at temperatures from 1.8 K to 8.5 K and magnetic fields from 0 T to 22 T are displayed. This is the first STM capable of atomic-resolution imaging and dI/dV measurement at 1.8 K in a 22 T water-cooled magnet. The high immunity to the magnetic field makes the nonmetallic tip-sample mechanical loop widely useable for atomic-resolution STM imaging in ultra-high magnetic field conditions.

A Cryostat Applicable to Long-Wavelength Light-Driven Scanning Probe Microscopy.

Recently, there has been growing interest in using lightwave-driven scanning probe microscopy (LD-SPM) to break through the Abbe diffraction limit of focusing, yielding insight into various energy couplings and conversion processes and revealing the internal information of matter. We describe a compact and efficient optical cryostat designed for LD-SPM testing under magnetic fields. The exceptional multilayer radiation shielding insert (MRSI) forms an excellent temperature gradient when filled with heat conducting gas, which removes the requirement to install an optical window in the liquid helium cooling shell. This not only critically avoids the vibration and thermal drift caused by solid heat conduction but also minimizes light transmission loss. The application of gate valves and bellows allows a simpler and more effective replacement of the sample and working cell in the test cavity. ANSYS software is used for steady-state thermal analysis of the MRSI to obtain the temperature distribution and heat transfer rate, and the necessity of the flexible copper shielding strips is illustrated by the simulations. The topography and magnetic domain images of 45 nm-thick La0.67Ca0.33MnO3 thin films on NdGaO3(001) substrates under a magnetic field were obtained by a self-made lightwave-driven magnetic force microscope in this cryostat. The resolution and noise spectra during imaging reveal temperature stability and low vibration throughout the cryostat. The experience acquired during the development of this cryostat will help to establish cryostats of similar types for a variety of optic applications requiring the use of cryogenic temperatures.

Cryogenic spectroscopic imaging scanning tunnelling microscope in a water-cooled magnet down to 1.7 K.

Spectroscopic-imaging scanning tunnelling microscope (SI-STM) in a water-cooled magnet (WM) at low temperature has long been desirable in the condensed matter physics area since it is crucial for addressing various scientific problems, such as the behaviour of Cooper electrons crossing Hc2 in a high-temperature superconductor. Here we report on the construction and performance of the first atomically resolved cryogenic SI-STM in a WM. It operates at low temperatures of down to 1.7 K and in magnetic fields of up to 22 T (the WM's upper safety limit). The WM-SI-STM unit features a high-stiffness sapphire-based frame with the lowest eigenfrequency being 16 kHz. A slender piezoelectric scan tube (PST) is coaxially embedded in and glued to the frame. A well-polished zirconia shaft is spring-clamped onto the gold-coated inner wall of the PST to serve both the stepper and the scanner. The microscope unit as a whole is elastically suspended in a tubular sample space inside a 1K-cryostat by a two-stage internal passive vibrational reduction system, achieving a base temperature below 2 K in a static exchange gas. We demonstrate the SI-STM by imaging TaS2 at 50 K and FeSe at 1.7 K. Detecting the well-defined superconducting gap of FeSe, an iron-based superconductor, at variable magnetic fields demonstrates the device's spectroscopic imaging capability. The maximum noise intensity at the typical frequency is 3 pA per square root Hz at 22 T, which is only slightly worse than at 0 T, indicating the insensitivity of the STM to harsh conditions. In addition, our work shows the potential of SI-STMs for use in a WM and hybrid magnet with a 50 mm-bore size where high fields can be generated.