Controlling the Spin Polarization of the Electron Current in a Semimagnetic Resonant-Tunneling Diode

The spin filtering effect of the electron current in a double-barrier resonant-tunneling diode (RTD) consisting of ZnMnSe semimagnetic layers has been studied theoretically. The influence of the distribution of the magnesium ions on the coefficient of the spin polarization of the electron current has been investigated. The dependence of the spin filtering degree of the electron current on the external magnetic field and the bias voltage has been obtained. The effect of the total spin polarization of the electron current has been predicted. This effect is characterized by total suppression of the spin-up component of electron current, that takes place when the Fermi level coincides with the lowest Landau level for spin-up electrons in the RTD semimagnetic emitter

Strategie der schnittaufteilung. Еine wirksame methode zur leistungsanpassung und verbesserung des dynamischen schnittverhaltens beim planfräsen

Der Beitrag beinhaltet eine zusammenfassende Darstellung des Prinzips der Schnittaufteilung als Methode zur dynamischen Prozessstabilisierung beim Planfräsen. Es wird dargelegt, wie die Schnittaufteilung beim Fräsen durch die Kombination von WSP mit unterschiedlichen Formen prinzipiell realisiert werden kann. Neben der Erläuterung weiterer positiver Effekte wird auf die Nutzung der Schnittaufteilung zur Leistungsanpassung unter stabilen Bearbeitungsbedingungen eingegangen.В статті розглядається ефективний метод регулювання потужності фрезерування та покращення динамічних характеристик фрезерування. Запропоновано стратегію скорочення проходів

Curvature-driven homogeneous Dzyaloshinskii-Moriya interaction and emergent weak ferromagnetism in anisotropic antiferromagnetic spin chains

Chiral antiferromagnets are currently considered for broad range of applications in spintronics, spin-orbitronics and magnonics. In contrast to the established approach relying on materials screening, the anisotropic and chiral responses of low-dimensional antifferromagnets can be tailored relying on the geometrical curvature. Here, we consider an achiral, anisotropic antiferromagnetic spin chain and demonstrate that these systems possess geometry-driven effects stemming not only from the exchange interaction but also from the anisotropy. Peculiarly, the anisotropy-driven effects are complementary to the curvature effects stemming from the exchange interaction and rather strong as they are linear in curvature. These effects are responsible for the tilt of the equilibrium direction of vector order parameters and the appearance of the homogeneous Dzyaloshinskii-Moriya interaction. The latter is a source of the geometry-driven weak ferromagnetism emerging in curvilinear antiferromagnetic spin chains. Our findings provide a deeper fundamental insight into the physics of curvilinear antiferromagnets beyond the $\sigma$-model and offer an additional degree of freedom in the design of spintronic and magnonic devices.Comment: 5 pages, 3 figures, 1 table, 33 references, supplementary informatio

Investigation of surface structure, electrokinetic and stability properties of highly dispersed Ho₂O₃-Yb₂O₃/SiO₂ nanocomposites

A series of highly dispersed Ho2O3–Yb2O3/SiO2 nanocomposites was synthesized using a liquid-phase method and examined using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM), Scanning Electron Microscopy (SEM), and photon correlation spectroscopy (PCS). X-ray fluorescence spectrometry (XRF) confirmed a similar amount of weight percentage of Ho, Yb and Si oxides in the prepared samples. Samples HoYbSi1 (Ho2O3:Yb2O3:SiO2 = 0.5:10:89.5, wt. %), HoYbSi2 (Ho2O3:Yb2O3:SiO2 = 1:10:89, wt. %) and HoYbSi3 (Ho2O3:Yb2O3:SiO2 = 2:10:88, wt. %) calcined at 550 °C are amorphous. TEM and SEM analysis confirm a sphere-like morphology with a quite homogeneous size and shape. As compared with the initial silica, the agglomerated particles of nanocomposites in the aqueous medium are in the range from 200 to 850 nm according to PCS data. The effect of anionic polyacrylic acid (PAA) adsorption on fumed silica (SiO2) and Ho2O3–Yb2O3/SiO2 nanocomposite surfaces on suspension stability was studied. The turbidymetry method was used to monitor the initial silica and triple nanooxides suspensions stability as a function of time

Field-induced spin reorientation transitions in antiferromagnetic ring-shaped spin chains

Easy axis antiferromagnets are robust against external magnetic fields of moderate strength. Spin reorientations in strong fields can provide an insight into more subtle properties of antiferromagnetic materials, which are often hidden by their high ground state symmetry. Here, we investigate theoretically effects of curvature in ring-shaped antiferromagnetic achiral anisotropic spin chains in strong magnetic fields. We identify the geometry-governed helimagnetic phase transition above the spin-flop field between vortex and onion states. The curvature-induced Dzyaloshinskii-Moriya interaction results in the spin-flop transition being of first- or second-order depending on the ring curvature. Spatial inhomogeneity of the N\'eel vector in the spin-flop phase generates weak ferromagnetic response in the plane perpendicular to the applied magnetic field. Our work contributes to the understanding of the physics of curvilinear antiferromagnets in magnetic fields and guides prospective experimental studies of geometrical effects relying on spin-chain-based nanomagnets.Comment: 11 pages, 6 figure

Psychosomatic organism disorders in peptic ulcer of the stomach and duodenum

Велику частину гастроентерологічних захворювань займає пептична виразка шлунку та дванадцятипалої кишки. Особливу роль у даному захворюванні відіграє психоемоційний стан пацієнта, особливо в умовах тотальної урбанізації, коли стресові фактори виключити із життя неможливо, що і призводять до психосоматичних захворювань

Paramagnetic centers in amorphous and microcrystalline silicon irradiated with 2 МeV electrons

Amorphous and microcrystalline silicon are well known materials for thin film large area electronics. The defects in the material are an important issue for the device quality and the manufacturing process optimization. We study defects in thin film silicon with electron spin resonance (ESR). In order to vary the defect density in a wide range 2 MeV electron bombardment at 100 K was applied with dose as high as 10¹⁸ e*cm⁻². Samples were investigated after deposition, after irradiation and between the annealing steps. The spin density (Ns) in the material was varied over 3 orders of magnitude. Strong satellites with g≈2.010 and g≈2.000 were observed on the shoulders of the dangling bond line. The initial Ns and the shape of the resonance line were restored after annealing.Аморфний і мікрокристалічний кремній є широко відомими матеріалами для виробництва тонкоплівкової електроники великої площі. Дефекти у даних матеріалах відіграють вирішальну роль для якості пристроїв і оптимізації виробничих процесів. Ми досліджували тонкоплівковий гідрогенований кремній методом вимірів електронного парамагнитного резонансу (ЕПР). Для зміни щільності дефектів у широкому диапазоні зразки було опромінено електронами з енергією 2 МеВ. Зразки було досліджено після осадження, після опромінення і між етапами відпалу. Щільність спинів (Ns) в матеріалі змінювалась в межах 3-х порядків величини. З обох боків від центрального резонансу, що характеризує обірвані зв’язки кремнію, спостеригались потужні додаткові резонансні лінії (g≈2.010 и g≈2.000). Після відпалу форма резонансних ліній і щільність спинів поверталися до вихідних показників.Аморфный и микрокристаллический кремний являются широко известными материалами для производства тонкопленочной электроники большой площади. Дефекты в данных материалах играют решающую роль для качества приборов и оптимизации производственных процессов. Мы исследовали тонкопленочный гидрогенированный кремний методом измерений электронного парамагнитного резонанса (ЭПР). Для изменения плотности дефектов в широких пределах образцы облучались электронами с энергией 2 МэВ. Образцы исследовались после осаждения, после облучения и между стадиями отжига. Плотность спинов (Ns) в материале изменялась в пределах 3-х порядков величины. По обе стороны от центрального резонанса, характеризующего оборванные связи кремния, наблюдались мощные дополнительные резонансные линии (g≈2.010 и g≈2.000). После отжига форма резонансных линий и плотность спинов возвращались к исходным значениям

First Measurement of the Tensor Structure Function b1b_1 of the Deuteron

The \Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6 GeV/c positron beam of \Hera. The use of a tensor polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry \At and the tensor structure function \bd for average values of the Bj{\o}rken variable $0.01<0.45$ and of the squared four-momentum transfer $0.5 {\rm GeV^2} <5 {\rm GeV^2}$. The quantities \At and \bd are found to be non-zero. The rise of \bd for decreasing values of $x$ can be interpreted to originate from the same mechanism that leads to nuclear shadowing in unpolarized scattering

Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target

Single-spin asymmetries for semi-inclusive electroproduction of charged pions in deep-inelastic scattering of positrons are measured for the first time with transverse target polarization. The asymmetry depends on the azimuthal angles of both the pion ($\phi$) and the target spin axis ($\phi_S$) about the virtual photon direction and relative to the lepton scattering plane. The extracted Fourier component \cmpi is a signal of the previously unmeasured quark transversity distribution, in conjunction with the so-called Collins fragmentation function, also unknown. The Fourier component \smpi of the asymmetry arises from a correlation between the transverse polarization of the target nucleon and the intrinsic transverse momentum of quarks, as represented by the previously unmeasured Sivers distribution function. Evidence for both signals is observed, but the Sivers asymmetry may be affected by exclusive vector meson productio

Search for an exotic S=-2, Q=-2 baryon resonance at a mass near 1862 MeV in quasi-real photoproduction

A search for an exotic baryon resonance with $S=-2, Q=-2$ has been performed in quasi-real photoproduction on a deuterium target through the decay channel $\Xi^- \pi^- \to \Lambda \pi^- \pi^- \to p \pi^- \pi^- \pi^-$. No evidence for a previously reported $\Xi^{--}(1860)$ resonance is found in the $\Xi^- \pi^-$invariant mass spectrum. An upper limit for the photoproduction cross section of 2.1 nb is found at the 90% confidence level. The photoproduction cross section for the $\Xi^{0}(1530)$ is found to be between 9 and 24 nb