Perovskite manganites are viewed as one of the key building blocks of oxide spintronics devices due to their attractive physical properties. However, cation off-stoichiometry at epitaxial interfaces between manganites and other materials can lead to interfacial dead layers, severely reducing the device performance. Here, transmission electron microscopy and synchrotron-based spectroscopy are used to demonstrate that oxygen vacancies during growth serve as a critical factor for modifying the cation stoichiometry in pulsed laser deposited La 0.8 Sr 0.2 MnO 3 fi lms. Near the fi lm/substrate (SrTiO 3 ) interface, A-site cations (La/Sr) are in excess when oxygen vacancies are induced during fi lm growth, partially substituting Mn. Simultaneously, Sr cations migrate towards the fi lm surface and form a SrO rock-salt monolayer. Consequentially, a gradient of the Mn nominal valence is observed along the fi lm growth direction, leading to anomalous magnetic properties. The results narrow the selection range of useful oxygen pressures during deposition and demonstrate that accurate cation stoichiometry can only be achieved after oxygen vacancies are eliminated during growth. This fi nding suggests that the oxygen pressure serves as a tuning parameter for the interfacial dead layers and, hence, for control over device properties.

We present evidence of topological surface states in β-Ag2Te through first-principles calculations, periodic quantum interference effect and ambipolar electric field effect in single crystalline nanoribbon. Our first-principles calculations show that β-Ag2Te is a topological insulator with a gapless Dirac cone with strong anisotropy. To experimentally probe the topological surface state, we synthesized high quality β-Ag2Te nanoribbons and performed electron transport measurements. The coexistence of pronounced Aharonov-Bohm oscillations and weak Altshuler-Aronov-Spivak oscillations clearly demonstrates coherent electron transport around the perimeter of β-Ag2Te nanoribbon and therefore the existence of topological surface states, which is further supported by the ambipolar electric field effect for devices fabricated by β-Ag2Te nanoribbons. The experimental evidences of topological surface states and the theoretically predicted anisotropic Dirac cone of β-Ag2Te suggest that the material may be a promising candidate of topological insulator for fundamental study and future spintronic devices.

It is well known that the magnetic state of the La0.7Sr0.3MnO3 (LSMO) thin-film heterostructure is strongly correlated with the lattice, spin, orbital, and charge states, since these influence the electric and magnetic transport properties even on the unit-cell level. Therefore, understanding the material's magnetic properties on the nanoscale is important for the development of novel applications. The recently developed electron magnetic-circular dichroism (EMCD) technique allows the determination of atomic site-specific magnetic information via the use of transmitted electrons; however, its sensitivity is not high enough to quantitatively acquire magnetic information in many weak magnetism systems. Here, we utilized a dynamical diffraction-effect assisted EMCD technique to quantitatively determine the spin and orbital magnetic moment of LSMO/SrTiO3 thin films on the nanometer scale using a transmission electron microscope. Further, data processing was optimized to enhance the intensity of the EMCD signals for manganese, which have very weak magnetism at room temperature. High signal-to-noise ratio and accurate quantitative magnetic measurement are eventually achieved. Finally, the spin magnetic moments (0.73 ± 0.26 μB) are derived, and we also limited the ratio of the orbital to spin magnetic moment within an interval of (−0.03, 0.01). Our results not only present the nanoscale magnetic parameters of LSMO/SrTiO3, but also demonstrate how the measurement limit of the spin (or orbital) magnetic moment can be achieved, which is via the developed dynamical diffraction effect assisted EMCD technique.

Using identified DEGs, significantly changed biological processes such as nucleic acid metabolic process and KEGG pathways such as cytokine-cytokine receptor interaction in PBMCs of HCC patients were identified. In addition, several important hub genes, for example, CUL4A, and interleukin (IL) 8 were also uncovered.

Ductile removal behavior of hard and brittle material in the process of machining has always been a sticking topic. A series of nanoscratch tests of K9 glass were conducted with Berkovich probe on nanoindenter XP to investigate the ductile removal process, material deformation and crack damage. It was found that the scratches surface was free from crack damage in the range of the selected scratching parameters and excellent machinability of K9 glass was obtained. The observation also showed that the stable chips were distributed on the sides of the scratches and the deformation of chips was much larger than that obtained in the conventional machining. Meanwhile, a pile-up phenomenon was obvious and the residual depth of scratches was decreased with the increasing of scratch velocity under the same normal load condition.