Random exchange effects in antiferromagnetic quantum spin chains: A Monte Carlo study

Schüttler, Heinz-Bernd; Scalapino, D. J.; Grant, P. M.

doi:10.1103/physrevb.35.3461

Cited by 9 publications

(4 citation statements)

References 30 publications

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“…The quasi-elastic scattering of diffusive origin shows a continuous overall decrease of intensity with decreasing temperature 60 to 30 K. Below 15 K, however, the intensity of the quasi-elastic scattering increases again. This peculiar temperature dependence points to a nontrivial origin of the low temperature signal [33][34][35], i.e. not to scattering on static lattice defects but to very low energy excitations of the spin system as they are predicted for doped spinons in substituted spin chains [33].…”

Section: Resultsmentioning

confidence: 99%

“…Recently, the theorectical study of non-magnetic impurities in spin chains and ladders gained interest as a first step towards understanding correlation effects in doped quantum spin systems [33,[36][37][38][39]. In earlier Monte Carlo studies of the spin susceptibility in random or disordered, non-dimerized spin chains a suppression of the long range AF correlations and an enhancement of the spin-Peierls instability was found [34,35]. Recent theoretical investigations of strongly dimerized spin chains show that non-magnetic impurities create loose s=1/2 spins which randomly introduce states within the magnetic excitation gap.…”

Section: Discussionmentioning

confidence: 99%

“…In earlier Monte Carlo studies of the spin susceptibility in random or disordered, non-dimerized spin chains a suppression of the long range AF correlations and an enhancement of the spin-Peierls instability was found [34,35]. Recent theoretical investigations of strongly dimerized spin chains show that non-magnetic impurities create loose s=1/2 spins which randomly introduce states within the magnetic excitation gap.…”

Section: Discussionmentioning

confidence: 99%

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Effects of in-chain and off-chain substitutions on spin fluctuationsin the spin-Peierls compoundCuGeO3

et al. 1997

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The effect of in-chain and off-chain substitutions on 1D spin fluctuations in the spin-Peierls compound CuGeO 3 has been studied using Raman scattering in order to understand the interplay between defect induced states, enhanced spin-spin correlations and the ground state of low dimensional systems. Inchain and off-chain substitutions quench the spin-Peierls state and induce 3D antiferromagnetic order at T≤5 K. Consequently a suppression of a 1D gap-induced mode as well as a constant intensity of a spinon continuum are observed at low temperatures. A 3D two-magnon density of states now gradually extends to higher temperatures T≤60 K compared with pure CuGeO 3 . This effect is more pronounced in the case of off-chain substitutions (Si) for which a Néel state occurs over a larger substitution range, starting at very low concentrations. Besides, additional low energy excitations are induced. These effects, i.e. the shift of a dimensional crossover to higher temperatures are due to an enhancement of the spin-spin correlations induced by a small amount of substitutions. The results are compared with recent Monte Carlo studies on substituted spin ladders, pointing to a similar instability of coupled, dimerized spin chains and spin ladders upon substitution. 75.50.Ee, 75.30.Et

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Effects of in-chain and off-chain substitutions on spin fluctuationsin the spin-Peierls compoundCuGeO3

et al. 1997

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“…Random matrix techniques have proved to be fruitful in addressing various problems in quantum information theory (QIT) [10,32,11] and theoretical physics [12,13]. In condensed matter physics (CMP), quantum spins with random exchange have been extensively studied with surprising phase transition behaviors [16,17,14,15].…”

Section: Elusive Spectra Of Hamiltoniansmentioning

confidence: 99%

Eigenvalues and Low Energy Eigenvectors of Quantum Many-Body Systems

Movassagh

2012

Preprint

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I first give an overview of the thesis and Matrix Product States (MPS) representation of quantum spin systems on a line with an improvement on the notation.The rest of this thesis is divided into two parts. The first part is devoted to eigenvalues of quantum many-body systems (QMBS). I introduce Isotropic Entanglement (IE), which draws from various tools in random matrix theory and free probability theory to accurately approximate the eigenvalue distribution of QMBS on a line with generic interactions. We then list some open related problems. Next, I discuss the eigenvalue distribution of one particle hopping random Schrödinger operator in one dimension from free probability theory in context of the Anderson model.There have been many great scientists who influenced my scientific life trajectory in positive ways. I am very grateful to Reinhard Nesper, Roald Hoffmann, Mehran Kardar, and Richard V. Lovelace. I also like to thank Otto E. Rössler, Jürg Fröhlich, John McGreevy, Jack Wisdom, Alexei Borodin and John Bush.I have been fortunate to have met so many wonderful people and made wonderful friendships during my PhD at MIT; too many to name here. I owe a good share of my happiness, balance in life, and the fun I had, to them. Last but certainly not least, I thank my dad, Javad Movassagh, and mom, Mahin Shalchi, for the biological existence and all they did for my sister and I to have a worthwhile future and an education. I dedicate this thesis to them.

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Numerical simulations of random spin (and fermionic) models with a wide distribution of energy scales

Bhatt

Wan

Kennett

et al. 2002

Computer Physics Communications

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Random exchange effects in antiferromagnetic quantum spin chains: A Monte Carlo study

Cited by 9 publications

References 30 publications

Effects of in-chain and off-chain substitutions on spin fluctuationsin the spin-Peierls compoundCuGeO3

Effects of in-chain and off-chain substitutions on spin fluctuationsin the spin-Peierls compoundCuGeO3

Eigenvalues and Low Energy Eigenvectors of Quantum Many-Body Systems

Numerical simulations of random spin (and fermionic) models with a wide distribution of energy scales

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