Spin density wave in oxypnictide superconductors in a three-band model

The spin density wave and its temperature dependence in oxypnictide are studied in a three-band model. The spin susceptibilities with various interactions are calculated in the random phase approximation(PPA). It is found that the spin susceptibility peaks around the M point show a spin density wave(SDW) with momentum (0, $\pi$) and a clear stripe-like spin configuration. The intra-band Coulomb repulsion enhances remarkably the SDW but the Hund's coupling weakens it. It is shown that a new resonance appears at higher temperatures at the $\Gamma$ point indicating the formation of a paramagnetic phase. There is a clear transition from the SDW phase to the paramagnetic phase.Comment: 4 pages,8 figure

Conductance modulation in spin field-efect transistors under finite bias voltages

The conductance modulations in spin field-effect transistors under finite bias voltages were studied. It was shown that when a finite bias voltage is applied between two terminals of a spin field-effect transistor, the spin precession states of injected spin-polarized electrons in the semiconductor channel of the device will depend not only the gate-voltage controlled Rashba spin-orbit coupling but also depend on the bias voltage and, hence, the conductance modulation in the device due to Rashba spin-orbit coupling may also depend sensitively on the bias voltage.Comment: 7 pages, 3 figures, to appear in Physical Review B, (April, 2004

Effects of spin imbalance on the electric-field driven quantum dissipationless spin current in pp-doped Semiconductors

It was proposed recently by Murakami et al. [Science \textbf{301}, 1348(2003)] that in a large class of $p$-doped semiconductors, an applied electric field can drive a quantum dissipationless spin current in the direction perpendicular to the electric field. In this paper we investigate the effects of spin imbalance on this intrinsic $spin$ Hall effect. We show that in a real sample with boundaries, due to the presence of spin imbalance near the edges of the sample, the spin Hall conductivity is not a constant but a sensitively $position$-$dependent$ quantity, and due to this fact, in order to take the effects of spin imbalance properly into account, a microscopic calculation of both the quantum dissipationless spin Hall current and the spin accumulation on an equal footing is thus required. Based on such a microscopic calculation, a detailed discussion of the effects of spin imbalance on the intrinsic spin Hall effect in thin slabs of $p$-doped semiconductors are presented.Comment: 8 pages, 2 figures, An extended version with detailed calculations To appear in Phys. Rev.

Some symmetry properties of spin currents and spin polarizations in multi-terminal mesoscopic spin-orbit coupled systems

We study theoretically some symmetry properties of spin currents and spin polarizations in multi-terminal mesoscopic spin-orbit coupled systems. Based on a scattering wave function approach, we show rigorously that in the equilibrium state no finite spin polarizations can exist in a multi-terminal mesoscopic spin-orbit coupled system (both in the leads and in the spin-orbit coupled region) and also no finite equilibrium terminal spin currents can exist. By use of a typical two-terminal mesoscopic spin-orbit coupled system as the example, we show explicitly that the nonequilibrium terminal spin currents in a multi-terminal mesoscopic spin-orbit coupled system are non-conservative in general. This non-conservation of terminal spin currents is not caused by the use of an improper definition of spin current but is intrinsic to spin-dependent transports in mesoscopic spin-orbit coupled systems. We also show that the nonequilibrium lateral edge spin accumulation induced by a longitudinal charge current in a thin strip of \textit{finite} length of a two-dimensional electronic system with intrinsic spin-orbit coupling may be non-antisymmetric in general, which implies that some cautions may need to be taken when attributing the occurrence of nonequilibrium lateral edge spin accumulation induced by a longitudinal charge current in such a system to an intrinsic spin Hall effect.Comment: 11 pages, 6 figure

Spin resolved Hall effect driven by spin-orbit coupling

Spin and electric Hall currents are calculated numerically in a two-dimensional mesoscopic system with Rashba and Dresselhaus spin-orbit coupling by means of the Landauer-Buttiker formalism. It is found that both electric and spin Hall currents circulate when two spin-orbit couplings coexist, while the electric Hall conductance vanishes if either one is absent. The electric and spin Hall conductances are suppressed in strong disorder, but survive in weak disorder. Physically it can be understood that the spinomotive transverse "force" generated by spin-orbit coupling is responsible for the formation of the spin Hall current and the lack of transverse reflection symmetry is the origin of the electric Hall current.Comment: 4 pages, 5 figure

Influences of spin accumulation on the intrinsic spin Hall effect in two dimensional electron gases with Rashba spin-orbit coupling

In a two dimensional electron gas with Rashba spin-orbit coupling, the external electric field may cause a spin Hall current in the direction perpendicular to the electric field. This effect was called the intrinsic spin Hall effect. In this paper, we investigate the influences of spin accumulation on this intrinsic spin Hall effect. We show that due to the existence of boundaries in a real sample, the spin Hall current generated by the intrinsic spin Hall effect will cause spin accumulation near the edges of the sample, and in the presence of spin accumulation, the spin Hall conductivity will not have a universal value. The influences of spin accumulation on the intrinsic spin Hall effect in narrow strips of two dimensional electron gases with Rashba spin-orbit coupling are investigated in detail.Comment: 7 pages, 2 figure

GC-MS analysis of essential oil from Anethum graveolens L (dill) seeds extracted by supercritical carbon dioxide

Purpose: To conduct gas chromatography-mass spectrometric (GC-MS) analysis of the chemical compositions of dill seed essential oil (DSEO) obtained by supercritical CO2. Methods: The impact on extraction yield were examined by single factor test, the particle size of dill seed, extraction temperature, time, pressure, as well as CO2 flux. The best extraction conditions were obtained by an orthogonal test. The chemical configurations of essential oil were examined by GC-MS analysis. Results: The optimal extraction conditions included an extraction time of 120 min, particle size of 60 mesh, CO2 flow of 25 L/h, temperature of 40oC, and pressure of 20 MPa. Under these conditions, the yield of essential oil was 6.7 %. Out of 38 recognized compounds, the main ones were D-carvone (40.36 %), D-limonene (19.31 %), apiol (17.50 %), α-pinene (6.43 %), 9-octadecenoic acid (9.00 %) as well as 9,12-octadecadienoic acid (2.44 %). Conclusion: A total of 38 constituents of the essential oil obtained by supercritical CO2 were identified. The findings may provide a theoretical basis for comprehensive utilization of dill seed essential oil (DSEO) from China

Kinetic magnetoelectric effect in a 2D semiconductor strip due to boundary-confinement induced spin-orbit coupling

In a thin strip of a two-dimensional semiconductor electronic system, spin-orbit coupling may be induced near both edges of the strip due to the substantial spatial variation of the confining potential in the boundary regions. In this paper we show that, in the presence of boundary-confinement induced spin-orbit coupling, a longitudinal charge current circulating through a 2D semiconductor strip may cause \textit{strong} non-equilibrium spin accumulation near both edges of the strip. The spins will be polarized along the normal of the 2DEG plane but in opposite directions at both edges of the strip. This phenomenon is essentially a kinetic magnetoelectric effect from the theoretical points of view, but it manifests in a very similar form as was conceived in a spin Hall effect.Comment: 7 pages, 4 fig

lncRNA profiling to elucidate the metabolic mechanism of green tea extract on weight loss in mice

Purpose: To understand the effects of green tea extract on weight loss at the gene level using long non-coding RNA (lncRNA) expression profiles. Methods: lncRNA expression signatures in rats fed two different diets were determined by analyzing previously published gene expression profiles in Gene Expression Omnibus (GEO). The lncRNAs specific to rats in a particular dietary group were confirmed using an additional autonomous dataset. LncRNA expression profiles were compared to explore the underlying mechanisms of green tea extract on weight loss. Results: Three lncRNAs (Gm38399, F730035P03Rik, and 5033430I15Rik) that may be the targets of green tea and that may play crucial roles in the lipid-lowering effects of green tea were identified. Using functional annotation databases, two of the targets of two of the lncRNAs were identified as Nav1 and Atxn1. Conclusion: Based on annotation databases, green tea extract may affect metabolic processes in adipocytes by regulating the lncRNAs GM38399 and 5033430I15Rik that modulate their cis-regulatory target genes Nav1 and Atxn1, respectively. Nav1 and Atxn1 may then regulate trans-regulatory lncRNAs