Correlation functions for 1d interacting fermions with spin-orbit coupling

We compute correlation functions for one-dimensional electron systems which spin and charge degrees of freedom are coupled through spin-orbit coupling. Charge density waves, spin density waves, singlet- triplet- superconducting fluctuations are studied. We show that the spin-orbit interaction modify the exponents and the phase diagram of the system, changing the dominant fluctuations and making new susceptibilities diverge for low temperature.Comment: 5 pages, 3 figures. Accepted for publication in Phys. Rev.

Primary disability due to neoplasms in Ukraine: structure, trends, influencing factors

A full study was conducted using the statistical method of research in order to analyze the status and structure of primary disability of the adult population of the regions of Ukraine due to tumors in the period ща 2010–2019 and identify the causes that affect the indicators of primary disability and regional characteristics. We have performed the analysis of expanded statistical information regarding disability in Ukraine with the help of the "Report on the causes of disability, indications for medical, professional and social rehabilitation" (form № 14, approved by order of the Ministry of Health of Ukraine in coordination with State Statistics Committee of Ukraine dated 10.07.2007 № 378) within 24 regions of Ukraine and Kyiv over the last ten years. In addition, the correlation analysis was performed using Microsoft Excel© to find the connection between primary disability due to neoplasms and a number of medical and social factors using Pearson-Brave correlation coefficient (r). Over the last ten years, the rates of primary disability due to neoplasms and malignant tumors of both adults and able-bodied population have been increasing steadily. They have always been among the top three causes of disability in Ukraine. However, cardiovascular diseases occupied the first place over the last 27 years. In 2019, tumors took the first place. Fluctuations in primary disability due to neoplasms are connected with a number of medical and non-medical causes. The main ones are morbidity, prevalence of neoplasms, number of beds in cancer dispensaries and availability of specialized oncology medical expert commissions in the region, changes in legislation regarding criteria for assessing disability groups. In the structure of primary disability due to neoplasms people of working age (40-60 years) dominate, their number varies by year, but the tendency to predominance persists Among the disability groups a severe second disability group dominates, which indicates a late diagnosis due to untimely treatment of these people and the predominance of the so-called "neglected" forms of the disease. This trend takes place during the observation period of all ten years.  The highest rates of primary disability due to neoplasms are also stable throughout the ten-year observation period and are observed in the regions that are considered the most affected by Chornobyl disaster: Kyiv region, Kyiv, Zhytomyr, Chernihiv, Volyn, Rivne. However, the increase in this indicator in Poltava region over the last three years is not entirely motivated. The obtained results will be the basis for the development of national and regional measures for the rehabilitation of people with disabilities caused by tumors and contribute to public funds saving due to their targeted distribution in regions and keeping labor resources

Spin Accumulation in Quantum Wires with Strong Rashba Spin-Orbit Coupling

We present analytical and numerical results for the effect of Rashba spin-orbit coupling on band structure, transport, and interaction effects in quantum wires when the spin precession length is comparable to the wire width. In contrast to the weak-coupling case, no common spin-quantization axis can be defined for eigenstates within a single-electron band. The situation with only the lowest spin-split subbands occupied is particularly interesting because electrons close to Fermi points of the same chirality can have approximately parallel spins. We discuss consequences for spin-dependent transport and effective Tomonaga-Luttinger descriptions of interactions in the quantum wire.Comment: 4 pages, 4 figures, expanded discussion of spin accumulatio

Spin transport of electrons through quantum wires with spatially-modulated strength of the Rashba spin-orbit interaction

We study ballistic transport of spin-polarized electrons through quantum wires in which the strength of the Rashba spin-orbit interaction (SOI) is spatially modulated. Subband mixing, due to SOI, between the two lowest subbands is taken into account. Simplified approximate expressions for the transmission are obtained for electron energies close to the bottom of the first subband and near the value for which anticrossing of the two lowest subbands occurs. In structures with periodically varied SOI strength, {\it square-wave} modulation on the spin transmission is found when only one subband is occupied and its possible application to the spin transistor is discussed. When two subbands are occupied the transmission is strongly affected by the existence of SOI interfaces as well as by the subband mixing

Tops and Writhing DNA

The torsional elasticity of semiflexible polymers like DNA is of biological significance. A mathematical treatment of this problem was begun by Fuller using the relation between link, twist and writhe, but progress has been hindered by the non-local nature of the writhe. This stands in the way of an analytic statistical mechanical treatment, which takes into account thermal fluctuations, in computing the partition function. In this paper we use the well known analogy with the dynamics of tops to show that when subjected to stretch and twist, the polymer configurations which dominate the partition function admit a local writhe formulation in the spirit of Fuller and thus provide an underlying justification for the use of Fuller's "local writhe expression" which leads to considerable mathematical simplification in solving theoretical models of DNA and elucidating their predictions. Our result facilitates comparison of the theoretical models with single molecule micromanipulation experiments and computer simulations.Comment: 17 pages two figure

Spin Precession and Oscillations in Mesoscopic Systems

We compare and contrast magneto-transport oscillations in the fully quantum (single-electron coherent) and classical limits for a simple but illustrative model. In particular, we study the induced magnetization and spin current in a two-terminal double-barrier structure with an applied Zeeman field between the barriers and spin disequilibrium in the contacts. Classically, the spin current shows strong tunneling resonances due to spin precession in the region between the two barriers. However, these oscillations are distinguishable from those in the fully coherent case, for which a proper treatment of the electron phase is required. We explain the differences in terms of the presence or absence of coherent multiple wave reflections.Comment: 9 pages, 5 figure

Effect of bulk inversion asymmetry on the Datta-Das transistor

A model of the Datta-Das spin field-effect transistor is presented which, in addition to the Rashba interaction, takes into account the influence of bulk inversion asymmetry of zinc-blende semiconductors. In the presence of bulk inversion asymmetry, the conductance is found to depend significantly on the crystallographic orientation of the channel. We determine the channel direction optimal for the observation of the Datta-Das effect in GaAs and InAs-based devices.Comment: 4 pages, Revtex4, 4 EPS figure

Physical properties of nanocrystaline PbS synthesized by electrolytic method

The possibility of obtaining nanocrystaline lead sulfide by an electrolytic method using lead electrodes is demonstrated, and the influence of temperature on the synthesis process is investigated. Based on the results of X-ray diffraction studies, the chemical and phase composition of the obtained samples is determined, as well as the parameters of the unit cell of the crystals lattice. The size of the nanocrystallites and the magnitude of residual mechanical strain in them is determined using the methods of Debye-Scherrer and Williamson-Hall. The results of X-ray diffraction are in agreement with the results of the Raman scattering on phonons

Quantum spin pumping with adiabatically modulated magnetic barrier's

A quantum pump device involving magnetic barriers produced by the deposition of ferro magnetic stripes on hetero-structure's is investigated. The device for dc- transport does not provide spin-polarized currents, but in the adiabatic regime, when one modulates two independent parameters of this device, spin-up and spin-down electrons are driven in opposite directions, with the net result being that a finite net spin current is transported with negligible charge current. We also analyze our proposed device for inelastic-scattering and spin-orbit scattering. Strong spin-orbit scattering and more so inelastic scattering have a somewhat detrimental effect on spin/charge ratio especially in the strong pumping regime. Further we show our pump to be almost noiseless, implying an optimal quantum spin pump.Comment: 14 pages, 9 figures. Manuscript revised with additional new material on spin-orbit scattering and inelastic scattering. Further new additions on noiseless pumping and analytical results with distinction between weak and strong pumping regimes. Accepted for publication in Physical Review