Hasil untuk "cond-mat"

M. V. Rossum

In my thesis I study mesoscopic corrections on diffuse transport. I first describe the diffuse transport of light, using the scalar approximation and the radiative transfer approach. Next, I focus on the correlations in transmission, I discuss the so called C_1, C_2, C_3 decomposition and calculate each term in detail. Finally, I discuss the full distribution functions in the transmission. Many references and figures are included. Note, however, that much of the work was already published or is present on the cond-mat archive. A limited number is available as hardcopy on request (vrossum@phys.uva.nl) else 132 pages Postscript.

Joaquín J. García, G. Subías, J. Blasco et al.

In a recent letter, J. P. Wright et al [Phys. Rev. Lett. 87,266401 (2001) and cond-mat/0111119] have investigated the crystal structure of magnetite below the Verwey transition temperature (TV) by means of X-ray and neutron powder diffraction. We show that the interpretation given by J. P. Wright et al. is unsupported by their own crystallographic data which demonstrate, instead, the lack of atomic long-range CO in magnetite below the Verwey transition.

E. Marinari, G. Parisi, J. Ruiz-Lorenzo

We show that the dynamical behavior of the 3D Ising spin glass with Gaussian couplings is not compatible with a droplet dynamics. We show that this is implied from the data of reference cond-mat/9904143, that, when analyzed in an accurate way, give multiple evidences of this fact. Our study is based on the analysis of the overlap-overlap correlation function, at different values of the separation r and of the time t.

G. Setlur

Based on ideas introduced in a previous preprint cond-mat/9701206 we propose an exactly solvable model of bosons interacting amongst themselves via a Van-der Waal-like repulsive interaction, and compute both the filling fraction and the dynamical structure factor exactly. The novelty of this approach involves introducing, analogous to Fermi sea (or surface) displacements, Bose fields that in this case, correspond to fluctuations of the Bose condensate. The exact dynamical structure factor has a coherent part that corresponds to the Bogoliubov spectrum and an incoherent part that is a result of correlations.

C. Burgess, C. Lutken

We construct the low-energy effective theory for the SO(5) model of high-Tc superconductivity, recently proposed by S.C. Zhang (cond-mat/9610140). This permits us to develop a systematic expansion for low-energy observables in powers of the small symmetrybreaking interactions. The approximate SO(5) symmetry predicts relations amongst these observables, which are model-independent consequences of Zhang’s proposed symmetrybreaking pattern.

A. Travesset

We discuss the properties of Skyrmions in the Fractional Quantum Hall effect (FQHE). We begin with a brief description of the Chern-Simons-Landau-Ginzburg description of the FQHE, which provides the framework in which to understand a new derivation of the properties of FQHE Skyrmions (S. Baez, A. P. Balachandran, A. Stern and A. Travesset cond-mat 9712151) from anomaly and edge considerations.

J. Denlinger, J. Clack, J. Allen et al.

This paper has been withdrawn by the authors due to new theoretical evidence and experimental proof that the semiconducting bandgap reported in this paper and ascribed to a surface region is in fact a bulk property of divalent hexaborides. As reported in J. D. Denlinger et al., cond-mat/0107429, which supercedes this paper, bulk-sensitive boron K-edge soft x-ray emission provides a complementary confirmation of the X-point band gap identified by angle-resolved photoemission.

G. Gunaratne

Disordered networks of fragile elastic elements have been proposed as a model of inner porous regions of large bones [Gunaratne et.al., cond-mat/0009221, this http URL]. It is shown that the ratio $\Gamma$ of responses of such a network to static and periodic strain can be used to estimate its ultimate (or breaking) stress. Since bone fracture in older adults results from the weakening of porous bone, we discuss the possibility of using $\Gamma$ as a non-invasive diagnostic of osteoporotic bone.

F. Essler, F. Gohmann, V. Korepin

We comment on the preprint cond-mat/9805103 by D. Braak and N. Andrei \cite{BrAn98}. We point out that the ``new'' Bethe Ansatz equations presented in \cite{BrAn98} are identical to the Bethe equations for strings introduced by M. Takahashi for the description of thermodynamics in 1972 \cite{Takahashi72}. Some physics suggested in \cite{BrAn98} is incorrect. In particular, all former conclusions made on the basis of the string Bethe equations remain valid.

Y. Barash, A. A. Svidzinskii

S. Simon, P. Lee

Volovik and Kopnin make two seperate points regarding our recent paper (S. H. Simon and P. A. Lee, PRL 78, 1548 (1997); cond-mat/9611133). First they note that the scaling regime we address in our paper is limited by the curvature of the Fermi surface, and secondly they note that the crossover scale derived in our paper is incorrect. These points are valid and are discussed in this reply. With the exception of the incorrectly predicted crossover scale, the results of our paper remain unchanged.

J. Lidmar

Recently, Aji and Goldenfeldt [Phys. Rev. Lett. 87, 197003 (2001), cond-mat/0105622] put forward an explanation for the value of the dynamic critical exponent z observed in certain Monte Carlo simulations of the superconducting phase transition in zero magnetic field. In this Comment, we point out that their analysis is based on incorrect assumptions regarding the scaling dimension of the vortex density.

G. Volovik

We show that the clean superconductor with line of gap nodes is not in conflict with the Nernst theorem. The answer to the question in the title of the Schopohl-Dolgov paper in Phys. Rev. Lett. 80 (1998) 4761 (cond-mat/9802264) is yes.

M.Hotta

This paper has been withdrawn by the author and the content is merged into a new paper: H-Theorem and Generalized Entropy Composition with Different q Indices: cond-mat/9912454.

K. Ziegler, M. Hettler, P. Hirschfeld

In a recent Comment (cond-mat/9701197) on our Letter (PRL 77, 3013 (1996), cond-mat/9604176) Nersesyan and Tsvelik questioned the relevance of our exact calculation of the density of states (DOS) of a 2D d-wave superconductor using a Lorentzian disorder distribution, claiming ``that models with Lorentzian and Gaussian disorder belong to different universality classes'', on grounds of a comparison with a straightforward perturbation expansion in the disorder potential. We showed in a very recent paper (cond-mat/9703047) that a rigorous nonzero lower bound for DOS can be established without relying on the tails of the disorder distribution, i.e. both the Gaussian and Lorentzian distributions belong to a large class of distributions which give a nonzero lower bound for the DOS. This proves that the result of our Letter is generic.

V. Gurarie, A. Zee

This preprint has been withdrawn as crucial errors have been discovered in the papers it has referred to. It is now superseded by cond-mat/9807391.

E. P. Rodrigues, M. Barbosa, L. Costa

The analytical calculation of the self-referred lacunarity is used as a validation standard of the computational algorithm. In this supplementary material to our article (see cond-mat/0407079) we present a detailed calculation for two simple shapes, namely a square box and a cross.

J. C. Flores

K.Yu.Bliokh

Comment on S.-Q. Shen, Phys. Rev. Lett. 95, 187203 (2005) [cond-mat/0506676]. We show that the equations of motion deduced by Shen are incorrect and derive semiclassical expression for the operator of force, which also contains a term of the transverse spin force but twice as large in magnitude.

B. Bernevig, D. Giuliano, R. Laughlin

We make some comments about the results we obtained in Phys. Rev. Lett. 86,3392(2001), and in Phys. Rev. Lett.87, 177206 (2001), and show that the conclusion of a recent paper [cond-mat/0409495] leveling some criticism on our results is, in fact, incorrect