Hedgehog spin texture and competing orders associated with strains on the surface of a topological crystalline insulator

We have investigated spin reorientation phenomena and interaction driven effects under the presence of applied strains on the (001) surface of Pb$_{1-x}$Sn$_x$(Te, Se) topological crystalline insulators, which host multiple Dirac cones. Our analysis is based on a four-band $k\cdot p$ model, which captures the spin and orbital textures of the surface states at low energies around the $\bar{X}$ and $\bar{Y}$ points, including the Lifshitz transition. Even without breaking the time-reversal symmetry, we find that certain strains which break the mirror symmetry can induce hedgehog-like spin texture associated with gap formation at the Dirac points. The Chern number of the gapped surface ground state is shown to be tunable through the interplay of strains and a perpendicular Zeeman field. We also consider effects of strain in the presence of interactions in driving competing orders, and obtain the associated phase diagram at the mean-field level. Potential applications of our results for low power consuming electronics are discussed.Comment: 11 pages, 9 figures, and two table

Automatic inspection system for dimensional measurements of the saw blade milling cutter

The demand for measuring equipments of automatic optical inspection has grown rapidly, because of its benefits of promoted efficiency and higher precision. Instead of manual projection measurements, measurement performance and efficiency can be obviously enhanced by the image measurement system. In this investigation, digital image processing and geometrical measurement principles have been integrated to develop a dynamic measurement system for the dimensional measurements of a saw blade milling cutter. The repeatability of the measurement system has been analyzed and its accuracy has been verified by using commercial 3D image measurement system. The analysis results show that the dimensional precision of 25μm and the angular precision of 0.21° can be realized by the self-developed measurement system. Between the results of the developed system and reference standard system, there are 25μm deviation in dimensional measurement and 0.26° in angular measurement. That measuring performances can meet the industrial requirement and the higher measurement efficiency can be achieved.Peer Reviewe

Using Focused Electron Beams to Drill Straight Nanopores on a Membrane

A high-resolution focused electron beam is used for the fabrication of metal nanostructures and devices with insulating membranes by nanosculpting metal films. This top-down focused electron beam drilling method uses the controlled ablation of materials to produce nanoscale devices with near-atomic precision of order. Using the proposed procedure, nano-drilling is not directly realized through the aperture, but by using a focused electron beam to burn away the solvent. Recent studies have investigated silicon nitride nanopores with an hourglass profile and silica nanopores with a pyramid-shaped cross-section, but electronic drilling in these approaches failed to produce straight nanopores. A method is proposed to improve the membranes’ thermal conductivity to rapidly produce straight nanopores, and is experimentally confirmed and has significant potential for use in nano-sensors or nano-devices.</p

Development and Optimization of a Differential Signal-Based Fabry-Perot Interferometer for Nanopositioning

In this study, we present the optimization of a Fabry-Perot interferometer with a differential signal utilized as the laser encoder to meet the stringent demands of nanopositioning. The proposed system aims to enhance stability and accuracy in nanopositioning applications by leveraging the common path structure and coaxial characteristics of Fabry-Perot interferometers. To improve the resolution of this system, an interpolation module is employed to increase the laser encoder resolution to 15.82 nm. Compared to the simulated interference signal from traditional Fabry-Perot interferometers, the differential interference signal proposed in this study is more sinusoidal, thus reducing errors in resolution subdivision. To verify the correspondence between the actual interference signal and the simulated one, a signal testing experiment is implemented in this study. Eventually, the experimental signal results demonstrate that the actual light intensity signals match the simulated results, indicating that this signal can be significantly beneficial for use as a laser encoder

Präzisionsprüfgerät für Nanomesstaster

Precision Test Equipment for Nano Gauging Probes Abstract Due to the increasing demands on the processing tolerance in manufacturing technology and on the miniaturization of industrial components, nanometrology is increasingly more important in manufacturing processes. Therefore, precise measuring instruments and sensors play a decisive role for the accurate characterization and inspection of products. For linear length inspection, highly accurate gauging probes, i.e. nano gauging probes, are of great importance. They possess a resolution within the nanometer range and have an accuracy of less than 100 nm. This group of precision gauging probes includes probes based on electronic as well as optical principles, e.g. inductive, incremental-optical or interference optical. To guarantee the accuracy and the traceability to the definition of the meter, calibration and test of nano gauging probes are necessary. Existing test methods and machines suffer from various disadvantages. Some permit only manual test procedures which are time-consuming, e.g. with high accurate gauge blocks as material measures. Other tests exhibit higher accuracy but are capable of measuring only in the micrometer range or result in uncertainties of more than 100 nm in the large measuring ranges. In order to make the test possible with a high resolution as well as a large measuring range, a precision test equipment for nano gauging probes was constructed, that with a resolution of 1.24 nm, a measuring range up to 20 mm (60 mm) and a measuring uncertainty of approx. ±10 nm can fulfill the requirements of high resolution within the nanometer range while simultaneously covering a large measuring range in the order of millimeters. This work is based on a calibration equipment for length sensors developed at the Institute of Process Measurement and Sensor Technology at the Ilmenau Technical University. The precision test equipment is equipped with a plane mirror interferometer. As a new approach for the avoidance of the Abbe error, a continuous angular control of the measuring body is realized with the help of piezo translators. Thus, during the test procedure, the measuring body reaches a tilt of less than 0.2" is reached and the Abbe error is minimized. A drive system consisting of ball guides, a fine thread spindle and a DC motor positions the measuring body. For the automation of the test procedure a measuring program adhering to the measurement principle outlined in VDI/VDE 2617 guideline was designed. With this program a gauging probe can be tested in less than thirty minutes with eleven measuring points and five repetitions. Theoretical and experimental investigations show that the precision test equipment has a test uncertainty of approx. ±10 nm at the measuring range of 18 mm, that corresponds to a relative uncertainty of approx. ±5·10-7. With small uncertainty, the minimization of the Abbe error and short test times this device can be regarded as an universal and efficient precision test equipment, which is available for the accurate test of arbitrary precision gauging probes and other linear length sensors

Linear Displacement and Straightness Measurement by Fabry-Perot Interferometer Integrated with an Optoelectronic Module

This research develops a three degrees of freedom (DOF) measurement system by integrating Fabry-Perot interferometer and photoelectronic inspection module to determine linear displacement, horizontal and vertical straightness geometric error parameters simultaneously. The interferometer and the photoelectronic inspection module in a three DOF measurement system share the same light source, and the two structures are used to measure linear displacement and straightness errors. The experimental results are utilized to calculate the relevant error parameters according to ISO standards and numerical analysis. They show that after the machine error compensation, the positioning deviation of the system is reduced from 55 μm to 19 μm, corresponding to the reduction of 65%. The accuracy is promoted from 65 μm to 31 μm, about the improvement of 52%. The horizontal and vertical straightness errors of the machine are 4.30 μm and 5.71 μm respectively

Crushing Strength Sampling With Minimal Damage to Taiwania (Taiwania Cryptomerioides) Using a Fractometer

The Fractometer is a device that stresses radial increment cores in the direction of the fiber to measure crushing strength, which can provide a direct wood quality indicator for structural lumber. This study analyzes the pattern of the radial variation in Taiwania (Taiwania cryptomerioides Hay.) trunk wood crushing strength to explore its effect on the precision and efficiency of the sampling procedure in the outer increment core zone as an alternate nondestructive sampling method. A pith-to-bark 0.5-cm caliber core was extracted at breast height (1.3 m above the ground) from each tree and was separated into individual section groups. Then individual crushing strengths were determined using the Fractometer.In this study, the variation in crushing strength in the transverse direction increased from the pith outward to the bark side. An analysis of variance and correlation analysis were used to evaluate the data. The magnitude of the radial variation in crushing strength was smaller than the tree-to-tree variation. Including samples of at least 7.2 cm, 5.4 cm, and 2.4 cm near the bark side was found to be acceptable for the assessment of wood crushing strength for trees of Type A (DBH > 27 cm), Type B (DBH = 23~27 cm), and Type C (DBH > 23 cm), respectively

Molecular Mechanisms of Neuronal Development

Neuronal development relies on the coordination of various biological mechanisms, including the trafficking and function of neurotransmitter receptors and synaptic cell adhesion molecules (CAMs). In this dissertation, I investigated various distinct, yet related, mechanisms of neuronal development: the roles of synaptic adhesion-like molecules (SALMs) in neurite outgrowth and cell adhesion, and the transient expression of N-methyl D-aspartate receptors (NMDARs) at growth cones of young hippocampal neurons. First, I showed that the SALMs, a newly discovered family of CAMs, regulate changes in neurite outgrowth with distinct morphological characteristics. Through transfections of primary hippocampal neurons, I investigated the roles of each SALM in neurite outgrowth. In addition to neurite outgrowth, SALMs are involved in synapse formation. In a parallel study, I further investigated SALM function in development by examining the formation of SALM-mediated cell-cell contacts, and their implications on synaptogenesis. In my final study, I investigated the transient expression of NMDARs at axonal growth cones of young hippocampal neurons. While NMDAR function at synapses is well known, their roles earlier in development are less characterized. The data indicate that NMDARs are present and functional at axonal growth cones of young hippocampal neurons. Somatic whole-cell recordings of young neurons reveal NMDAR-mediated currents in response to local application of NMDA at axonal growth cones, while calcium imaging experiments show that these NMDARs elicit localized calcium influx. Together, the studies in this dissertation give insights into the recurring phenomena of proteins and mechanisms that have dual/multiple roles throughout neuronal development. While a considerable amount of information is known about various biological events that occur at opposite ends of the developmental spectra, the mechanisms connecting them are often enigmatic, but can be elucidated through examining the proteins that they share in common