3,196 research outputs found

    Thomas-Fermi Method For Particles Obeying Generalized Exclusion Statistics

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    We use the Thomas-Fermi method to examine the thermodynamics of particles obeying Haldane exclusion statistics. Specifically, we study Calogero-Sutherland particles placed in a given external potential in one dimension. For the case of a simple harmonic potential (constant density of states), we obtain the exact one-particle spatial density and a {\it closed} form for the equation of state at finite temperature, which are both new results. We then solve the problem of particles in a x2/3 x^{2/3} ~ potential (linear density of states) and show that Bose-Einstein condensation does not occur for any statistics other than bosons.Comment: 10 pages (TeX), 2 figures available upon reques

    Effective mass of composite fermion: a phenomenological fit in with anomalous propagation of surface acoustic wave

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    We calculate the conductivity associated with the anomalous propagation of a surface acoustic wave above a two-dimensional electron gas at ν=1/2\nu=1/2. Murthy-Shankar's middle representation is adopted and a contribution to the response functions beyond the random phase approximation has been taken into account. We give a phenomenological fit for the effective mass of composite fermion in with the experimental data of the anomalous propagation of surface acoustic wave at ν=1/2\nu=1/2 and find the phenomenological value of the effective mass is several times larger than the theoretical value mth=6ϵ/e2l1/2m_{th}^*=6\epsilon/e^2l_{1/2} derived from the Hartree-Fock approximation. We compare our phenomenologically fitting composite fermion effective mass with those appeared in the measurements of the activation energy and the Shubnikov-de Haas effect and find that our result is fairly reasonable.Comment: 8 pages, 5 figures, the longer version of cond-mat/9801131 with crucial corrections, accepted for publication by PR

    Novel correlations in two dimensions: Some exact solutions

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    We construct a new many-body Hamiltonian with two- and three-body interactions in two space dimensions and obtain its exact many-body ground state for an arbitrary number of particles. This ground state has a novel pairwise correlation. A class of exact solutions for the excited states is also found. These excited states display an energy spectrum similar to the Calogero-Sutherland model in one dimension. The model reduces to an analog of the well-known trigonometric Sutherland model when projected on to a circular ring.Comment: 8 pages, REVTE

    Evolution of Magnetism in Single-Crystal Honeycomb Iridates

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    We report the successful synthesis of single-crystals of the layered iridate, (Na1x_{1-x}Lix_{x})2_2IrO3_3, 0x0.90\leq x \leq 0.9, and a thorough study of its structural, magnetic, thermal and transport properties. The new compound allows a controlled interpolation between Na2_2IrO3_3 and Li2_2IrO3_3, while maintaing the novel quantum magnetism of the honeycomb Ir4+^{4+} planes. The measured phase diagram demonstrates a dramatic suppression of the N\'eel temperature, TNT_N, at intermediate xx suggesting that the magnetic order in Na2_2IrO3_3 and Li2_2IrO3_3 are distinct, and that at x0.7x\approx 0.7, the compound is close to a magnetically disordered phase that has been sought after in Na2_2IrO3_3 and Li2_2IrO3_3. By analyzing our magnetic data with a simple theoretical model we also show that the trigonal splitting, on the Ir4+^{4+} ions changes sign from Na2_2IrO3_3 and Li2_2IrO3_3, and the honeycomb iridates are in the strong spin-orbit coupling regime, controlled by \jeff=1/2 moments.Comment: updated version with more dat

    ANALYTICAL APPLICATIONS OF SAFRANIN O

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    A simple and sensitive spectrophotometric method has been developed for the estimation of Mycophenolic acid. The method is based on the formation of   Ion-Association complex with MYCO formed an ion -association complex with basic dye, SafraninO. The cationic form of the dye SAFO involves in the formation of neutral coloured ion-association complexe with negative charge (acid groups in the drug) which is extractable into chloroform and behaves as a single unit being held together by electrostatic attraction. The absorption maxima were found to be at lMax 520 nm. The method obeys Beer's law within the limits 10-40µg/ml and gives reproducible results. Molar absorptivity value is obtained as8.424x104 L mol-1 cm-1 and recovery was found to be 99.17 ± 0.92 to 99.62 ± 0.27. Interferences of the other ingredients and excipients were not observed. The proposed method can be used for the determination of MYCO both in pure and pharmaceutical formulations. KeyWords: Mycophenolicacid (MYCO), SafraninO (SAFO), Ion- association Comple

    Exactly solvable toy models of unconventional magnetic alloys: Bethe Ansatz versus Renormalization Group method

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    We propose toy models of unconventional magnetic alloys, in which the density of band states, ρ(ϵ)\rho(\epsilon), and hybridization, t(ϵ)t(\epsilon), are energy dependent; it is assumed, however, that t2(ϵ)ρ1(ϵ)t^2(\epsilon)\propto\rho^{-1}(\epsilon), and hence an effective electron-impurity coupling Γ(ϵ)=ρ(ϵ)t2(ϵ)\Gamma(\epsilon)=\rho(\epsilon)t^2(\epsilon) is energy independent. In the renormalization group approach, the physics of the system is assumed to be governed by Γ(ϵ)\Gamma(\epsilon) only rather than by separate forms of ρ(ϵ)\rho(\epsilon) and t(ϵ)t(\epsilon). However, an exact Bethe Ansatz solution of the toy Anderson model demonstrates a crucial role of a form of inverse band dispersion k(ϵ)k(\epsilon).Comment: A final version. A previous one has been sent to Archive because of my technical mistake. Sorr

    Hamiltonian Description of Composite Fermions: Aftermath

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    The Lowest Landau Level (LLL), long distance theory of Composite Fermions (CF) developed by Murthy and myself is minimally extended to all distances, guided by very general principles. The resulting theory is mathematically consistent, and physically appealing: we clearly see the electron and the vortices binding to form the CF. The meaning of the constraints, their role in ensuring compressibility of dipolar objects at ν=1/2\nu =1/2, and the observability of dipoles are clarified.Comment: Revised for publication in PRL, 4 - epsilon page

    Solitons in one-dimensional interacting Bose-Einstein system

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    A modified Gross-Pitaevskii approximation was introduced recently for bosons in dimension d2d\le2 by Kolomeisky {\it et al.} (Phys. Rev. Lett. {\bf 85} 1146 (2000)). We use the density functional approach with sixth-degree interaction energy term in the Bose field to reproduce the stationary-frame results of Kolomeisky {\it et al.} for a one-dimensional Bose-Einstein system with a repulsive interaction. We also find a soliton solution for an attractive interaction, which may be boosted to a finite velocity by a Galilean transformation. The stability of such a soliton is discussed analytically. We provide a general treatment of stationary solutions in one dimension which includes the above solutions as special cases. This treatment leads to a variety of stationary wave solutions for both attractive and repulsive interactions.Comment: Latex, 14 pages, No figur
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