Výsledky vyhledávání - "Niggemann, H."

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Spin-3/2 models on the Cayley tree -- optimum ground state approach

Autor: Niggemann, H., Zittartz, J.

We present a class of optimum ground states for spin-3/2 models on the Cayley tree with coordination number 3. The interaction is restricted to nearest neighbours and contains 5 continuous parameters. For all values of these parameters the Hamiltonia

Externí odkaz: http://arxiv.org/abs/cond-mat/9810147

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Optimum ground states for spin-3/2 ladders with two legs

Autor: Niggemann, H., Zittartz, J.

Publikováno v: J. Phys. A: Math. Gen. 31, p. 9819-9828 (1998)

We construct the exact ground state for an antiferromagnetic spin-3/2 model on the two-leg ladder as an optimum ground state. The ground state contains a discrete parameter "sigma"=+/-1 and a continuous parameter "a" which controls z-axis anisotropy.

Externí odkaz: http://arxiv.org/abs/cond-mat/9808342

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Mixed Heisenberg Chains. II. Thermodynamics

Autor: Niggemann, H., Uimin, G., Zittartz, J.

Publikováno v: J. Phys.: Condens. Matter 10, p. 5217-5236 (1998)

We consider thermodynamic properties, e.g. specific heat, magnetic susceptibility, of alternating Heisenberg spin chains. Due to a hidden Ising symmetry these chains can be decomposed into a set of finite chain fragments. The problem of finding the t

Externí odkaz: http://arxiv.org/abs/cond-mat/9712202

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Mixed Heisenberg Chains. I. The Ground State Problem

Autor: Niggemann, H., Uimin, G., Zittartz, J.

Publikováno v: J. Phys.: Condens. Matter 9 No 42, p. 9031-9042 (1997)

We consider a mechanism for competing interactions in alternating Heisenberg spin chains due to the formation of local spin-singlet pairs. The competition of spin-1 and spin-0 states reveals hidden Ising symmetry of such alternating chains.
Comm

Externí odkaz: http://arxiv.org/abs/cond-mat/9703206

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Quantum phase transition in spin-3/2 systems on the hexagonal lattice - optimum ground state approach

Autor: Niggemann, H., Klümper, A., Zittartz, J.

Publikováno v: Z.Phys. B104 (1997) 103-110

Optimum ground states are constructed in two dimensions by using so called vertex state models. These models are graphical generalizations of the well-known matrix product ground states for spin chains. On the hexagonal lattice we obtain a one-parame

Externí odkaz: http://arxiv.org/abs/cond-mat/9702178

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Optimum ground states for spin-$\frac{3}{2}$ chains

Autor: Niggemann, H., Zittartz, J.

Publikováno v: Z. Phys. B 101(2), p. 289-297 (1996)

We present a set of {\em optimum ground states} for a large class of spin-$\frac{3}{2}$ chains. Such global ground states are simultaneously ground states of the local Hamiltonian, i.e. the nearest neighbour interaction in the present case. They are

Externí odkaz: http://arxiv.org/abs/cond-mat/9602080

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IL-17 serum levels in psoriatic arthritis: Is there a correlation in early stages of freshly diagnosed Psoriasis Arthritis?

Autor: Becker-Capeller, D, El-Nawab-Becker, S, Niggemann, H, Krieger, T

Publikováno v: 46. Kongress der Deutschen Gesellschaft für Rheumatologie (DGRh), 32. Jahrestagung der Deutschen Gesellschaft für Orthopädische Rheumatologie (DGORh), Wissenschaftliche Herbsttagung der Gesellschaft für Kinder-und Jugendrheumatologie (GKJR); 20180919-20180922; Mannheim; DOCSpA.39 /20190205/

Background: Psoriasis (PsO) is a chronic inflammatory disease associated with other systemic disorders like cardiovascular diseases, metabolic syndromes and arthritis associated with tendonitis. Previously we could demonstrate in freshly diagnosed ps

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7c2f8ebe3428786e34693545abd43cd9

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