The Many Electron Ground State of the Adiabatic Holstein Model in Two and Three Dimensions

We present the complete ground state phase diagram of the Holstein model in two and three dimension considering the phonon variables to be classical. We first establish the overall structure of the phase diagram by using exact diagonalisation based Monte Carlo (ED-MC) on small lattices and then use a new ``travelling cluster'' approximation (TCA) for annealing the phonon degrees of freedom on large lattices. The phases that emerge include a Fermi liquid (FL), with no lattice distortions, an insulating polaron liquid (PL) at strong coupling, and a charge ordered insulating (COI) phase around half- filling. The COI phase is separated from the Fermi liquid by a regime of phase coexistence whose width grows with increasing electron-phonon coupling. We provide results on the electronic density of states, the COI order parameter, and the spatial organisation of polaronic states, for arbitrary density and electron-phonon coupling. The results highlight the crucial role of spatial correlations in this strong coupling problem.Comment: Final versio

Doped magnetic moments in a disordered electron system: insulator-metal transition, spin glass and `cmr'

Recent experiments on the amorphous magnetic semiconductor Gd_x Si_{1-x}, Phys. Rev. Lett. 77, 4652 (1996), ibid 83, 2266 (1999), ibid 84, 5411 (2000), ibid 85, 848 (2000), have revealed an insulator-metal transition (i-m-t), as a function of doping and magnetic field, a spin glass state at low temperature, and colossal magnetoresistance close to the i-m-t. There are also signatures of strong electron-electron interaction close to the i-m-t. Motivated by these results we examine the role of doped magnetic moments in a strongly disordered electron system. In this paper we study a model of electrons coupled to structural disorder and (classical) magnetic moments, through an essentially exact combination of spin Monte Carlo and fermion exact diagonalisation. Our preliminary results, ignoring electron-electron interactions, highlights the interplay of structural and magnetic `disorder' which is primarily responsible for the observed features in magnetism and transport.Comment: 12 pages, two column revtex, with 11 embedded figure

Integrated farming system for improving agricultural productivity

This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

Macroscopic Degeneracy and Emergent Frustration in a Honeycomb Lattice Magnet

Using a hybrid method based on fermionic diagonalization and classical Monte Carlo, we investigate the interplay between itinerant and localized spins, with competing double- and super-exchange interactions, on a honeycomb lattice. For moderate superexchange, a geometrically frustrated triangular lattice of hexagons forms spontaneously. For slightly larger superexchange a dimerized groundstate is stable that has macroscopic degeneracy. The presence of these states on a non-frustrated honeycomb lattice highlights a novel phenomenon in this itinerant electron system: emergent geometrical frustration and degeneracy.Comment: 4+ pages, 4 figures; published versio

Functional outcome of galeazzi fracture dislocation treated by open reduction and internal fixation with dynamic compression plate

Background: Galeazzi fracture involves fracture of the distal 1/3rd of   radius shaft associated with dislocation of distal radioulnar joint. Open reduction and rigid internal fixation of radius is goal standard treatment. The aim of this study was done to evaluate the functional outcome of Galeazzi fracture dislocation managed by open reduction and internal fixation of radius.Methods: The study was conducted in department of orthopaedics Government Medical college Jammu from December 2018 to February 2021. 30 patients of Galeazzi fracture dislocation were managed with Open reduction and internal fixation of Radius with plating and were followed up to evaluate the results.Results: Age of the patients ranged between 23 years to 60 years with a mean range of 42 years. 22 cases were male (73.3%), 8 cases were females (26.6%). In 19 cases injury was in right side and in 11 cases injury was in left side. In most of the cases injury was due to due to RTA (80%) and in rest of cases injury was due to fall from height (20%).Conclusions: Anatomic restoration of length of the radius with rigid internal fixation is key to satisfactory results in Galeazzi fracture dislocations and K-wire fixation of distal radio ulnar joint is not necessary if anatomic reduction of the joint is obtained by indirect means such as open reduction and internal fixation of the radius and immobilization.

Theoretical prediction of multiferroicity in double perovskite Y2_2NiMnO6_6

We put forward double perovskites of the R$_2$NiMnO$_6$ family (with $R$ a rare-earth atom) as a new class of multiferroics on the basis of {\it ab initio} density functional calculations. We show that changing $R$ from La to Y drives the ground-state from ferromagnetic to antiferromagnetic with $\uparrow\uparrow\downarrow\downarrow$ spin patterns. This E$^*$-type ordering breaks inversion symmetry and generates a ferroelectric polarization of few $\mu C/cm^2$. By analyzing a model Hamiltonian we understand the microscopic origin of this transition and show that an external electric field can be used to tune the transition, thus allowing electrical control of the magnetization.Comment: 4 pages, 3 figure

Electronic structure studies of Fe- ZnO nanorods by x-ray absorption fine structure

We report the electronic structure studies of well characterized polycrystalline Zn_{1-x}Fe_xO (x = 0.0, 0.01, 0.03, and 0.05) nanorods synthesized by a co-precipitation method through x-ray absorption fine structure (XAFS). X-ray diffraction (XRD) reveals that Fe doped ZnO crystallizes in a single phase wurtzite structure without any secondary phase. From the XRD pattern, it is observed that peak positions shift towards lower 2\theta value with Fe doping. The change in the peak positions with increase in Fe contents clearly indicates that Fe ions are replacing Zn ions in the ZnO matrix. Linear combination fittings (LCF) at Fe K-edge demonstrate that Fe is in mixed valent state (Fe3+/Fe2+) with a ratio of ~ 7:3 (Fe3+:Fe2+). XAFS data is successfully fitted to wurtzite structure using IFEFFIT and Artemis. The results indicate that Fe substitutes Zn site in the ZnO matrix in tetrahedral symmetry.Comment: 7 pages, 5 figures, 2 tables, regular articl

Functional results of compound extra articular tibial pilon fractures managed with hybrid external fixator

Background: Distal tibia fractures are difficult to treat. It is often difficult to assess the potential risk of surgical complications because of the variations in the clinical findings. Less subcutaneous tissue, limited blood supply and no muscle insertions are the factors that tend to make the healing of the soft tissue more complex. Compounding presents a great challenge for the treating surgeon regarding the treatment options.Methods: A total of 23 patients were included in the study based on the inclusion and exclusion criteria and were managed by hybrid external fixator as definitive treatment. They were kept in follow up for at least 6 months and were assessed using Ovadia and Beal’s objective and subjective scoring.Results: All patients achieved fracture union with 82% patients reporting excellent to good functional outcome. Pin site infections and ankle stiffness were most common complications.Conclusions: A very good outcome is achieved in compound extra articular tibial pilon fractures with the hybrid fixator technique. Adequate stability is provided and hence early motion and ambulation can be started

A General Approach of Authentication Scheme and its Comparative Study

The field of information security is a vast area which is continually evolving and expanding relative to network data and global communication security. This literature review contrasts the research that has been published in the area of cryptography and authentication protocols, by providing a comparative and analytical study to secure the web servers and services

Control of sulphur and minimisation of centre line segregation for Rail Steel

Rail is the most important constituent of the track structure and plays a very vital role in the reliability of railway system as a whole. Quality of rail steel with reference to its chemical composition has been a matter of prime importance for the manufacturers as well as Railways. Sulphur is a detrimental element in rails since it causes hot shortness during rolling, centerline segregation during casting, poor weldability for the rails etc. To improve quality of rails, a substantially low range of sulphur < 0.015% (Railway's specified norms <0.03%) has been targeted in Bhilai Steel Plant by adequate sulphur control measures in steelmaking process. A two stage desulphurisation treatment is now employed in which the blast furnace hot metal is first treated by co-injection of Mg and CaC reagents, and subsequent treatment with a 2 synthetic slag former (CaO-Al O ) added to the ladle during tapping from the Basic 2 3 Oxygen furnace. Improvement in the internal quality of the cast bloom has been established by introduction of Electro Magnetic Stirring. The centerline segregation is minimized vis-a-vis the properties of the cast product and rails improved by the successful implementation of step by step control measures