Layered Antiferromagnetism Induces Large Negative Magnetoresistance in the van der Waals Semiconductor CrSBr

The recent discovery of magnetism within the family of exfoliatable van der Waals (vdW) compounds has attracted considerable interest in these materials for both fundamental research and technological applications. However current vdW magnets are limited by their extreme sensitivity to air, low ordering temperatures, and poor charge transport properties. Here we report the magnetic and electronic properties of CrSBr, an air-stable vdW antiferromagnetic semiconductor that readily cleaves perpendicular to the stacking axis. Below its N\'{e}el temperature, $T_N = 132 \pm 1$ K, CrSBr adopts an A-type antiferromagnetic structure with each individual layer ferromagnetically ordered internally and the layers coupled antiferromagnetically along the stacking direction. Scanning tunneling spectroscopy and photoluminescence (PL) reveal that the electronic gap is $\Delta_E = 1.5 \pm 0.2$ eV with a corresponding PL peak centered at $1.25 \pm 0.07$ eV. Using magnetotransport measurements, we demonstrate strong coupling between magnetic order and transport properties in CrSBr, leading to a large negative magnetoresistance response that is unique amongst vdW materials. These findings establish CrSBr as a promising material platform for increasing the applicability of vdW magnets to the field of spin-based electronics

Defect structure of Czochralski silicon co-implanted with helium and hydrogen and treated at high temperature - pressure

Effect of stress created by Ar hydrostatic pressure (HP) up to 1.1 GPa during annealing at the high temperature (HT) 1070 K (HT-HP treatment) on microstructure of Czochralski grown silicon co-implanted with helium and hydrogen Si:(He,H) using the same doses of He+ and H₂+ (DH,He= 5·10¹⁶ cm⁻², at energy 50 and 150 keV, respectively) was investigated by means of X-ray (synchrotron) diffraction, transmission electron microscopy, and electrical measurements. The nanostructured sponge-like buried layers are formed in Si:(He,H) by annealing / high pressure treatment. Decreased interference, diffuse scattering and individual contrast are observed in the synchrotron topograms for HT-HP treated Si:(He,H). The treatment at 723 K and HP results in an additional donor formation as a sequence of the implantation-disturbed layer. The HP-mediated (retarded) out-diffusion of hydrogen and helium is in part responsible for the effects observed

Complete Strain Mapping of Nanosheets of Tantalum Disulfide

Quasi-two-dimensional (quasi-2D) materials hold promise for future electronics because of their unique band structures that result in electronic and mechanical properties sensitive to crystal strains in all three dimensions. Quantifying crystal strain is a prerequisite to correlating it with the performance of the device, and calls for high resolution but spatially resolved rapid characterization methods. Here we show that using fly-scan nano X-ray diffraction we can accomplish a tensile strain sensitivity below 0.001% with a spatial resolution of better than 80 nm over a spatial extent of 100 $\mu$m on quasi 2D flakes of 1T-TaS2. Coherent diffraction patterns were collected from a $\sim$ 100 nm thick sheet of 1T-TaS2 by scanning 12keV focused X-ray beam across and rotating the sample. We demonstrate that the strain distribution around micron and sub-micron sized 'bubbles' that are present in the sample may be reconstructed from these images. The experiments use state of the art synchrotron instrumentation, and will allow rapid and non-intrusive strain mapping of thin film samples and electronic devices based on quasi 2D materials

X-Ray Topography Using Synchrotron Radiation

X-ray diffraction topography is a widely used method to study crystal lattice defects by visualization. The properties of synchrotron radiation relevant to topography methods extend the possibilities of investigations. These properties are the following: a high intensity, a broad spectral range, a natural collimation, a linear polarization in the horizontal plane, and a pulsed time structure. The application of synchrotron radiation to X-ray topographic studies is described and some recent examples of experiments are presented

Synchrotron radiation white beam topography with an oscillating monochromator

Drawbacks of white beam topography with synchrotron radiation, such as intense fluorescence background, thermal strain, and radiation damage, can be avoided by filtering the beam with an oscillating perfect crystal monochromator. The advantage of the white beam technique, namely the imaging of a sample of poor quality, is maintained. The image contrast is even improved due to the suppression of higher harmonics. Topographs of a LiF crystal demonstrate the feasibility of the method

Lattice Deformation Studies in Silicon Implanted with High-Energy Protons

The deformation of crystal lattice in silicon implanted with protons ofenergy 1.6-9 MeV was studied by means of X-ray topography and double--crystal rocking curve measurements. The samples were investigated as-im-planted and after thermal and electron annealing. The surface relief of theimplanted part of the crystal was also revealed with optical methods. As-im-planted wafers exhibited spherical bending being convex at the implantedside. Thermal and electron annealing caused a dramatic increase in bend-ing of the implanted part while the bending of the remaining part of thesample was reduced. A characteristic behaviour of a double-crystal topo-graphic contrast in the annealed crystals was explained due to bending ofthe shot-through layer along the Gaussian profile

Lattice Deformation Studies in Silicon Implanted with High-Energy Protons

The deformation of crystal lattice in silicon implanted with protons ofenergy 1.6-9 MeV was studied by means of X-ray topography and double--crystal rocking curve measurements. The samples were investigated as-im-planted and after thermal and electron annealing. The surface relief of theimplanted part of the crystal was also revealed with optical methods. As-im-planted wafers exhibited spherical bending being convex at the implantedside. Thermal and electron annealing caused a dramatic increase in bend-ing of the implanted part while the bending of the remaining part of thesample was reduced. A characteristic behaviour of a double-crystal topo-graphic contrast in the annealed crystals was explained due to bending ofthe shot-through layer along the Gaussian profile

Ferrielastic Domain Structure Study in Ca3Mn2Ge3O12Ca_3Mn_2Ge_3O_{12} Garnet

The domain structure of MnGcG bulk monocrystal is studied by means of X-ray double-crystal topography as well as by white beam synchrotron radiation (SR) topography. The image simulation of SR experiment is performed and compared with experimental data. The evolution of the domain structure with temperature is discussed as well as the influence of different cooling treatments

The images of misfit dislocations in Bragg-case synchrotron section topography

Silicon epitaxial layers deposited on substrates doped with boron and containing certain amount of misfit dislocations were studied by means of back-reflection synchrotron section topography. Samples with different curvature determined by substrate thickness and status of their back sides were examined. When the curvature of the sample was negligible the section pattern consisted of two stripes corresponding, respectively, to the layer and to the substrate. Misfit dislocations were revealed in the direct contrast located mostly in the vicinity of the substrate stripe. In the samples with radius of curvature smaller than 100m additional interference fringes were observed in a wide area behind the main two stripes. The sequence of these interference fringes was dependent on the curvature of the sample and differed from that of bent substrate wafers of the similar curvature. As a consequence the images of misfit dislocations became much more extended and contained many characteristic details. The character of experimental misfit dislocation images both in the case of flat and bent crystals was reproduced using numerical integration of the Takagi-Taupin equations