Zobrazeno 1 - 10
of 202
pro vyhledávání: '"Pimentel, I."'
Autor:
Pimentel, I. R., De Dominicis, C.
Publikováno v:
J. Phys. A 47, 455001 (2014)
We develop a field theory for spin glasses using Replica Fourier Transforms (RFT). We present the formalism for the case of replica symmetry and the case of replica symmetry breaking on an ultrametric tree, with the number of replicas $n$ and the num
Externí odkaz:
http://arxiv.org/abs/1412.8688
Autor:
Dias, F. Carvalho, Pimentel, I. R.
Publikováno v:
Phys. Rev. B 71, 224412 (2005)
We calculate the spin correlation function and the magnetic longitudinal and transverse susceptibilities of a two-dimensional antiferromagnet doped with a small concentration of holes, in the t-J model. We find that the motion of holes generates spin
Externí odkaz:
http://arxiv.org/abs/cond-mat/0511459
Publikováno v:
Phys. Rev. B 73, 075109 (2006).
We study the persistent current and the Drude weight of a system of spinless fermions, with repulsive interactions and a hopping impurity, on a mesoscopic ring pierced by a magnetic flux, using a Density Matrix Renormalization Group algorithm for com
Externí odkaz:
http://arxiv.org/abs/cond-mat/0506654
Publikováno v:
Phys. Rev. B 65, 224420 (2002)
We study the transition of short range Ising spin glasses in a magnetic field, within a general replica symmetric field theory, which contains three masses and eight cubic couplings, that is defined in terms of the fields representing the replicon, a
Externí odkaz:
http://arxiv.org/abs/cond-mat/0204615
Publikováno v:
Eur. Phys. J. B 25, 361-372 (2002)
Symmetry considerations and a direct, Hubbard-Stratonovich type, derivation are used to construct a replica field-theory relevant to the study of the spin glass transition of short range models in a magnetic field. A mean-field treatment reveals that
Externí odkaz:
http://arxiv.org/abs/cond-mat/0202162
Publikováno v:
Phys. Rev. B 61, 1371 (2000)
We study the renormalization of the staggered magnetization of a two-dimensional antiferromagnet as a function of hole doping, in the framework of the t-J model. It is shown that the motion of holes generates decay of spin waves into ''particle-hole'
Externí odkaz:
http://arxiv.org/abs/cond-mat/0001289
Autor:
Velhinho, M. T., Pimentel, I. R.
Publikováno v:
Phys. Rev. B 61, 1043 (2000)
We study the Lyapunov exponent for electron and phonon excitations, in pure and random Fibonacci quasicrystal chains, using an exact real space renormalization group method, which allows the calculation of the Lyapunov exponent as a function of the e
Externí odkaz:
http://arxiv.org/abs/cond-mat/0001060
Publikováno v:
Brain Topography, vol. 11, no. 3, pp. 201, 1999
Purpose: The understanding of brain activity, and in particular events such as epileptic seizures, lies on the characterisation of the dynamics of the neural networks. The theory of non-linear dynamics provides signal analysis techniques which may gi
Externí odkaz:
http://arxiv.org/abs/physics/9911039
Publikováno v:
Phys.Rev.B 60, 12329 (1999)
We study the spin excitations and the transverse susceptibility of a two-dimensional antiferromagnet doped with a small concentration of holes in the t-J model. The motion of holes generates a renormalization of the magnetic properties. The Green's f
Externí odkaz:
http://arxiv.org/abs/cond-mat/9910474
Publikováno v:
Med. Biol. Eng. Comput. 37, 492, (1999)
A parasystole from a heart-transplant patient is analysed using a beat-to-beat RR interval time series obtained from an electrocardiogram (ECG). The dysrhythmia, resulting from the co-existence of two pacemakers, the sinus node and an ectopic focus,
Externí odkaz:
http://arxiv.org/abs/physics/9910021