Disorder effect of resonant spin Hall effect in a tilted magnetic field

We study the disorder effect of resonant spin Hall effect in a two-dimension electron system with Rashba coupling in the presence of a tilted magnetic field. The competition between the Rashba coupling and the Zeeman coupling leads to the energy crossing of the Landau levels, which gives rise to the resonant spin Hall effect. Utilizing the Streda's formula within the self-consistent Born approximation, we find that the impurity scattering broadens the energy levels, and the resonant spin Hall conductance exhibits a double peak around the resonant point, which is recovered in an applied titled magnetic field.Comment: 6 pages, 4 figure

Electric field modulation of topological order in thin film semiconductors

We propose a method that can consecutively modulate the topological orders or the number of helical edge states in ultrathin film semiconductors without a magnetic field. By applying a staggered periodic potential, the system undergoes a transition from a topological trivial insulating state into a non-trivial one with helical edge states emerging in the band gap. Further study demonstrates that the number of helical edge state can be modulated by the amplitude and the geometry of the electric potential in a step-wise fashion, which is analogous to tuning the integer quantum Hall conductance by a megntic field. We address the feasibility of experimental measurement of this topological transition.Comment: 4 pages, 4 figure

Magnetic anisotropy and reversal in epitaxial Fe/MgO(001) films revisited

We investigate the magnetization reversal in Fe/MgO(001) films with fourfold in-plane magnetic anisotropy and an additional uniaxial anisotropy whose orientation and strength are tuned using different growth geometries and post growth treatments. The previously adopted mechanism of 180^{o} domain wall nucleation clearly fails to explain the observed 180^{o} magnetization reversal. A new reversal mechanism with two successive domain wall nucleations consistently predicts the switching fields for all field orientations. Our results are relevant for a correct interpretation of magnetization reversal in many other epitaxial metallic and semiconducting thin films.Comment: 4 pages, 4 figure

Spin susceptibility of Anderson impurities in arbitrary conduction bands

Spin susceptibility of Anderson impurities is a key quantity in understanding the physics of Kondo screening. Traditional numerical renormalization group (NRG) calculation of the impurity contribution $\chi_{\textrm{imp}}$ to susceptibility, defined originally by Wilson in a flat wide band, has been generalized before to structured conduction bands. The results brought about non-Fermi-liquid and diamagnetic Kondo behaviors in $\chi_{\textrm{imp}}$, even when the bands are not gapped at the Fermi energy. Here, we use the full density-matrix (FDM) NRG to present high-quality data for the local susceptibility $\chi_{\textrm{loc}}$ and to compare them with $\chi_{\textrm{imp}}$ obtained by the traditional NRG. Our results indicate that those exotic behaviors observed in $\chi_{\textrm{imp}}$ are unphysical. Instead, the low-energy excitations of the impurity in arbitrary bands only without gap at the Fermi energy are still a Fermi liquid and paramagnetic. We also demonstrate that unlike the traditional NRG yielding $\chi_{\textrm{loc}}$ less accurate than $\chi_{\textrm{imp}}$, the FDM method allows a high-precision dynamical calculation of $\chi_{\textrm{loc}}$ at much reduced computational cost, with an accuracy at least one order higher than $\chi_{\textrm{imp}}$. Moreover, artifacts in the FDM algorithm to $\chi_{\textrm{imp}}$, and origins of the spurious non-Fermi-liquid and diamagnetic features are clarified. Our work provides an efficient high-precision algorithm to calculate the spin susceptibility of impurity for arbitrary structured bands, while negating the applicability of Wilson's definition to such cases.Comment: the published versio

Surface morphology and magnetic anisotropy of Fe/MgO(001) films deposited at oblique incidence

We have studied surface morphology and magnetic properties of Fe/MgO(001) films deposited at an angle varying between 0o and 60o with respect to the surface normal and with azimuth along the Fe[010] or the Fe[110] direction. Due to shadowing, elongated grains appear on the film surface for deposition at sufficiently large angle. X-ray reflectivity reveals that, depending on the azimuthal direction, films become either rougher or smoother for oblique deposition. For deposition along Fe[010] the pronounced uniaxial magnetic anisotropy (UMA) results in the occurrence of reversed two-step and of three-step hysteresis loops. For deposition along Fe[110] the growth-induced UMA is much weaker, causing a small rotation of the easy axes.Comment: 3 pages, 4 figure

RNA-Seq analysis uncovers non-coding small RNA system of Mycobacterium neoaurum in the metabolism of sterols to accumulate steroid intermediates

Additional file 6: Figure S2. Negative networks of differentially expressed sRNA candidates and their target genes. (a): Mn-CC/C; (b): Mn-9OHAD/CC; (c) Mn-ADD/CC; and (d): Mn-BNA/CC. Squares represent the upregulated (amaranth) or downregulated sRNA candidates (blue); circles represent the putative upregulated (red) or downregulated (green) target genes; links represent the regulation of sRNAs on their target genes

Preferential arrangement of uniform Mn nanodots on Si(111)-7x7 surface

Under proper growth conditions, ordered and uniform Mn nanodots were fabricated on the Si(111)-7x7 surface without the presence of a wetting layer. Furthermore, the Mn nanodots deposited onto the elevated substrates were observed to occupy preferentially on the faulted half unit cells (FHUCs) of the Si(111)-7x7 surface. This phenomenon implies that the Mn dots adsorbed on the FHUCs is more stable than those adsorbed on the unfaulted half unit cells (UFHUCs). Within the framework of quasiequilibrium thermodynamics, the energy difference between adsorption on the UFHUCs and the FHUCs was estimated to be 0.05eV. The intrinsic attractive potential wells on the FHUCs effectively trap the outdiffusion of Mn atoms, and consequently result in a preferential arrangement of islands with well-defined sizes

Astrometric Reduction of Saturnian Satellites with Cassini-ISS Images Degraded by Trailed Stars

Imaging Science Subsystem (ISS) mounted on the Cassini spacecraft has taken a lot of images, which provides an important source of high-precision astrometry of some planets and satellites. However, some of these images are degraded by trailed stars. Previously, these degraded images cannot be used for astrometry. In this paper, a new method is proposed to detect and compute the centers of these trailed stars automatically. The method is then performed on the astrometry of ISS images with trailed stars. Finally, we provided 658 astrometric positions between 2004 and 2017 of several satellites that include Enceladus, Dione, Tethys, Mimas and Rhea. Compared with the JPL ephemeris SAT427, the mean residuals of these measurements are 0.11 km and 0.26 km in right ascension and declination, respectively. Their standard deviations are 1.08 km and 1.37 km, respectively. The results show that the proposed method performs astrometric measurements of Cassini ISS images with trailed stars effectively