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The random antiferromagnetic two-leg and zigzag spin-1/2 ladders are investigated using the real space renormalization group scheme and their complete phase diagrams are determined. We demonstrate that the first system belongs to the same…

Strongly Correlated Electrons · Physics 2007-05-23 J. A. Hoyos , E. Miranda

The quantum $XY$ spin chain with the interactions decaying as a power law $1/r^{1+ \sigma}$ of the distance between spins $r$ was investigated with the exact diagonalization method. Here, the constituent spin is set to $S=1$, which enables…

Statistical Mechanics · Physics 2019-08-06 Yoshihiro Nishiyama

We use a tensor network renormalization group method to study random $S=2$ antiferromagnetic Heisenberg chains with alternating bond strength distributions. In the absence of randomness, bond alternation induces two quantum critical points…

Strongly Correlated Electrons · Physics 2023-12-18 Yen-Tung Lin , Shao-Fu Liu , Pochung Chen , Yu-Cheng Lin

We study the ferromagnetic phase transition in a randomly layered Heisenberg magnet using large-scale Monte-Carlo simulations. Our results provide numerical evidence for the infinite-randomness scenario recently predicted within a…

Statistical Mechanics · Physics 2015-03-19 Fawaz Hrahsheh , Hatem Barghathi , Thomas Vojta

We study the finite-size behavior of the low-lying excitations of spin-1/2 Heisenberg chains with dimerization and next-to-nearest neighbors interaction, J_2. The numerical analysis, performed using density-matrix renormalization group,…

Statistical Mechanics · Physics 2007-05-23 D. Controzzi , C. Degli Esposti Boschi , F. Ortolani , S. Pasini

The statistics of critical spin-spin correlation functions in Ising systems with non-frustrated disorder are investigated on a strip geometry, via numerical transfer-matrix techniques. Conformal invariance concepts are used, in order to…

Statistical Mechanics · Physics 2007-05-23 Jean C. Lessa , S. L. A. de Queiroz

We report on a systematic approach for the calculation of the negativity in the ground state of a one-dimensional quantum field theory. The partial transpose rho_A^{T_2} of the reduced density matrix of a subsystem A=A_1 U A_2 is explicitly…

Statistical Mechanics · Physics 2015-06-11 Pasquale Calabrese , John Cardy , Erik Tonni

By using Lanczos exact diagonalization and quantum Monte Carlo combined with stochastic analytic continuation, we study the dynamical properties of the $S=1$ antiferromagnetic Heisenberg chain with different strengths of bond disorder. In…

Strongly Correlated Electrons · Physics 2021-12-23 Jing-Kai Fang , Jun-Han Huang , Han-Qing Wu , Dao-Xin Yao

Previous work proposed a strong-disorder renormalization approach for the Anderson model, using it to calculate the density of states and the inverse participation ratio [Johri \& Bhatt, Phys.\ Rev.\ B {\bf 90} 060205(R) (2014)]. This is…

Disordered Systems and Neural Networks · Physics 2023-05-17 Rachel Wortis , Eamonn Campbell , Donovan Allum

The asymptotic dynamical correlation functions in one-dimensional spin chains are described by power-laws. The corresponding exponents characterize different bulk and boundary critical behavior. We present novel results for the logarithmic…

Strongly Correlated Electrons · Physics 2022-10-14 Imke Schneider , Ipsita Mandal , Polina Matveeva , Dominik Strassel , Sebastian Eggert

We introduce variants of the Ma-Dasgupta renormalization-group approach for random quantum spin chains, in which the energy-scale is reduced by decimation built on either perturbative or non-perturbative principles. In one non-perturbative…

Disordered Systems and Neural Networks · Physics 2009-11-13 Péter Lajkó

We study the interplay between disorder and a quasi periodic coupling array in an external magnetic field in a spin-1/2 XXZ chain. A simple real space decimation argument is used to estimate the magnetization values where plateaux show up.…

Strongly Correlated Electrons · Physics 2009-11-07 Marcelo Arlego

Using a numerically exact technique we study spin transport and the evolution of spin-density excitation profiles in a disordered spin-chain with long-range interactions, decaying as a power-law, $r^{-\alpha}$ with distance and $\alpha<2$.…

Disordered Systems and Neural Networks · Physics 2020-09-02 Benedikt Kloss , Yevgeny Bar Lev

We obtain the logarithmic corrections to the dynamic response function and NMR T_1 and T_{2G} rates in the spin-1/2 antiferromagnetic Heisenberg chain using perturbative renormalization group in the leading irrelevant operator. The result…

Strongly Correlated Electrons · Physics 2009-10-31 Victor Barzykin

The decay of (disorder-averaged) static spin correlation functions at T=0 for the one-dimensional spin-1/2 XXZ antiferromagnet with uniform longitudinal coupling $J\Delta$ and random transverse coupling $J\lambda_i$ is investigated by…

Condensed Matter · Physics 2009-10-28 Heinrich Röder , Joachim Stolze , Richard N. Silver , Gerhard Müller

Disorder free many-body localization (MBL) can occur in interacting systems that can dynamically generate their own disorder. We address the thermal-MBL phase transition of two isotropic Heisenberg spin chains that are quasi-periodically…

Disordered Systems and Neural Networks · Physics 2024-09-04 K. G. S. H. Gunawardana , Bruno Uchoa

We study, using functional renormalization (FRG), two copies of an elastic system pinned by mutually correlated random potentials. Short scale decorrelation depend on a non trivial boundary layer regime with (possibly multiple) chaos…

Disordered Systems and Neural Networks · Physics 2009-11-11 Pierre Le Doussal

We consider a family of Schr\"odinger operators supported by a periodic chain of loops connected either tightly or loosely through connecting links of the length $\ell>0$ with the vertex coupling which is non-invariant with respect to the…

Spectral Theory · Mathematics 2020-03-26 Marzieh Baradaran , Pavel Exner , Miloš Tater

By means of a numerical analysis using a non-Abelian symmetry realization of the density matrix renormalization group, we study the behavior of vector chirality correlations in isotropic frustrated chains of spin S=1 and S=1/2, subject to a…

Strongly Correlated Electrons · Physics 2008-04-22 I. P. McCulloch , R. Kube , M. Kurz , A. Kleine , U. Schollwock , A. K. Kolezhuk

In a series of two papers, we investigate the large deviations and asymptotic behavior of stochastic models of brain neural networks with random interaction coefficients. In this first paper, we take into account the spatial structure of…

Probability · Mathematics 2017-01-05 Tanguy Cabana , Jonathan Touboul