Voltage control of superconducting exchange interaction and anomalous Josephson effect

Exerting control of the magnetic exchange interaction in heterostructures is of both basic interest and has potential for use in spin-based applications relying on quantum effects. We here show that the sign of the exchange interaction in a spin-valve, determining whether the ferro- or antiferromagnetic configuration is favored, can be controlled via an electric voltage. This occurs due to an interplay between a nonequilibrium quasiparticle distribution and the presence of spin-polarized Cooper pairs. Additionally, we show that a voltage-induced distribution controls the anomalous supercurrent that occurs in magnetic Josephson junctions, obviating the challenging task to manipulate the magnetic texture of the system. This demonstrates that two key phenomena in superconducting spintronics, the magnetic exchange interaction and the phase shift generating the anomalous Josephson effect, can be controlled electrically. Our findings are of relevance for spin-based superconducting devices which in practice most likely have to be operated precisely by nonequilibrium effects.Comment: 4 pages, 3 figures, 10 subfigures, revised editio

Farmers' perception on risks in fruits and vegetables production: an empirical study of Uttar Pradesh

The perceptions of farmers about risks in production of fruits and vegetables have been analysed using structured survey method. The study is based on the survey of a total of 634 farmers, comprising 188 fruit farmers and 446 vegetable farmers, covering six districts of Uttar Pradesh, namely, Lucknow, Allahabad, Gorakhpur, Moradabad, Jhansi and Agra. The perceived priorities of farmers about major sources of risks in production of fruits and vegetables have been reported under ‘investment risks’, ‘socio-economic risks’, ‘environmental risks’, ‘production risks’ and ‘market risks’. In general, the price and production risks have been perceived as the most important sources of risk in production of fruits and vegetables in the area. The study has argued that public intervention can facilitate better risk management through improved information system, development of financial markets and promotion of market-based price and yield insurance schemes, thus ensuring that the marginal farmers are able to benefit from these interventions as well as participate in the emerging systems.Crop Production/Industries,

Field-free nucleation of antivortices and giant vortices in non-superconducting materials

Giant vortices with higher phase-winding than $2\pi$ are usually energetically unfavorable, but geometric symmetry constraints on a superconductor in a magnetic field are known to stabilize such objects. Here, we show via microscopic calculations that giant vortices can appear in intrinsically non-superconducting materials, even without any applied magnetic field. The enabling mechanism is the proximity effect to a host superconductor where a current flows, and we also demonstrate that antivortices can appear in this setup. Our results open the possibility to study electrically controllable topological defects in unusual environments, which do not have to be exposed to magnetic fields or intrinsically superconducting, but instead display other types of order.Comment: Revised version; 4 pages manuscript, 4 pages supplemental, 6 figure

Critical Temperature and Tunneling Spectroscopy of Superconductor-Ferromagnet Hybrids with Intrinsic Rashba-Dresselhaus Spin-Orbit Coupling

We investigate theoretically how the proximity effect in superconductor/ferromagnet hybrid structures with intrinsic spin-orbit coupling manifests in the density of states and critical temperature. To describe a general scenario, we allow for both Rashba and Dresselhaus type spin-orbit coupling. Our results are obtained via the quasiclassical theory of superconductivity, extended to include spin-orbit coupling in the Usadel equation and Kupriyanov--Lukichev boundary conditions. Unlike previous works, we have derived a Riccati parametrization of the Usadel equation with spin-orbit coupling which allows us to address the full proximity regime. First, we consider the density of states in both SF bilayers and SFS trilayers, where the spectroscopic features in the latter case are sensitive to the phase difference between the two superconductors. We find that the presence of spin-orbit coupling leaves clear spectroscopic fingerprints in the density of states due to its role in creating spin-triplet Cooper pairs. Unlike SF and SFS structures without spin-orbit coupling, the density of states in the present case depends strongly on the direction of magnetization. We show that the spin-orbit coupling can stabilize singlet superconductivity even in the presence of a strong exchange field $h \gg \Delta$. This leads to the possibility of a magnetically tunable minigap: changing the direction of the exchange field opens and closes the minigap. We also determine how the critical temperature $T_c$ of an SF bilayer is affected by spin-orbit coupling and demonstrate that one can achieve a spin-valve effect with a single ferromagnet. We find that $T_c$ displays highly non-monotonic behavior both as a function of the magnetization direction and the type and direction of the spin-orbit coupling, offering a new way to exert control over the superconductivity of proximity structures.Comment: 25 pages, 21 figures. Accepted for publication in Phys. Rev.

Solution of Two Linear Equation Singularly Perturbed of First Order PDE on Argument

تم اختيار نظامين من مسائل الحرجة المفردة الخطية للمشتقات جزئية من الرتبة الأولى. علما بان هذا النظام يعتمد على معلمه صغيرة وهذه المعلمة موجوده في طرفي النظام المعادلة . وأيضا برهنا على وحدانية هذه الحلول ومنتظمة ضمن المجال   وثم برهنة متقاربة اية رتبة.Two systems of linear singularly perturbed problems in first order partial derivatives were considered. This system depends on a small parameter, and the small parameter exists in the left and right hands of it. Also, we prove the uniqueness of this  solution  is uniform  in  the  space  and asymptotic approximation of any rank was constructed

Characterization of Iraqi sheep milk fat

Fatty acids have been identified in sheep milk by GC/MS technique and it compared with cow milk. Sheep milk was contained of Odd fatty acids which uncommon in cow milk fat such as cyclo and branch fatty acids. On the other hand, the results showed that the sheep milk fat has been contained of Conjugated fatty acids.  Sheep milk was used in manufacturing yogurt and total acidity percentage, total count of lactic acid Bactria and Conjugated linoleic acid (CLA) concentration have been increased during incubation period. Locally manufactured yogurt from sheep milk has been superiority with its antioxidant activity and reducing power and tying ability ferrous ion with yogurt manufactured from cow milk. Yogurt manufactured from sheep milk has ability to retardation corn oil oxidation at different incubation periods

Efficiency and Productivity Changes in the Indian Food Processing Industry: Determinants and Policy Implications

This paper analyses efficiency and productivity changes in 12 broad segments of food manufacturing industries during pre and post liberalisation periods, covering a period of two decades, from 1980-1981 to 2001-2002. The nonparametric Data Envelopment Analysis (DEA) approach is used to compute the Malmquist Total Factor Productivity (TFP) change, which has been further decomposed into efficiency and technical change. This paper also evaluates the performance of major inputs used in the food processing industry and identifies the causes of inefficiency across various segments. Based on the findings, the paper gives suggestions that can be used by policy makers and food processors in making decisions regarding various technical and managerial aspects to improve productivity and efficiency.Technical Efficiency, Total Factor Productivity (TFP), Food Processing, Data Envelopment Analysis (DEA), India, Productivity Analysis, Research Methods/ Statistical Methods, Q10, Q11, Q13,

Solution Non Linear Equation Singularly Perturbed Of First Order Ode On Argument In Critical Case

In this paper we have a first order ODE that contain a small argument in front of the derivative was the same as power  argument in  both of right – left hand equation, and we define asymptotic solution using this argument of the power 0 and 1. Also we prove that there exists a unique solution of the main equation. Key words : ordinary differential equation, singularly perturbed problems, asymptotic solution method