Disordered quantum spinsystems  Page description

Help  Print 
Back »
 

Details of project

  
Identifier
34183
Type K
Principal investigator Iglói, Ferenc
Title in Hungarian Rendezetlen kvantum spinrendszerek
Title in English Disordered quantum spinsystems
Panel Physics 1
Department or equivalent Theoretical Solid State Physics Dept. (Research Institute for Solid State Physics and Optics Hung. Acad. Sci.)
Participants Juhász, Róbert
Starting date 2001-01-01
Closing date 2005-12-31
Funding (in million HUF) 4.490
FTE (full time equivalent) 0.00
state closed project





 

Final report

  
Results in Hungarian
Különböző sokrészecskés rendszerek (kvantum spinláncok, létrák és réteges rendszerek; klasszikus spinrendszerek és sztochasztikus folyamatok, stb.) kooperatív viselkedését vizsgáltuk rendezetlenség jelenlétében. Speciális renormálási csoport eljárást használva megállapítottuk, hogy számos vizsgált problémánánál a rendezetlenségi fluktuációk domináns szerepet játszanak a determinisztikus (termikus, kvantum, sztochasztikus) fluktuációkkal szemben. A kvantum spinláncoknál ismert végtelenül rendezetlen és erősen rendezetlen fixpont fogalmát kiterjesztettük klasszikus rendszerekre és sztochasztikus folyamatokra is. Több egydimenziós probléma esetén (rendezetlen kvantum Ising modell, rendezetlen kontakt folyamat, rendezetlen aszimmetrikus kizárási folyamat, stb.) a szinguláris tulajdonságokat aszimptotikusan egzaktul meghatároztuk, mind a kritikus pontban, mind azon kívül az un. Griffiths fázisban. Vizsgáltuk a rendezetlenség erősségének változásakor tapasztalható átmeneteket is.
Results in English
We have studied the cooperative behaviour of different manyparticle systems (quantum spin chains, ladders and layered systems; classical spin systems and stochastic processes, etc.) in the presence of quenched disorder. Using a special renormalization group procedure we have found that for several studied problems the disorder fluctuations play a dominant role over deterministic (thermal, quantum or stochastic) fluctuations. The concept of infinite disorder and strong disorder fixed points, known for random quantum spin chains has been extended to classical systems and stochastic processes, too. For several one-dimensional problems (random quantum Ising model, random contact process, random asymmetric exclusion process, etc.) the singular properties are asymptotically exactly determined, both at the critical point and outside the critical point, in the so called Griffiths phase. We have also studied the cross-overs by varying the strength of the disorder.
Full text http://real.mtak.hu/12/
Decision
Yes





 

List of publications

  
L. Turban and F. Iglói: Surface induced disorder and aperiodic perurbations at first-order trasitions, Phys. Rev. B66, 014440, 1-10, 2002
R. Melin, Y-C. Lin, P. Lajkó, H. Rieger and F. Iglói: Strongly disordered spin ladders, Phys. Rev. B65, 104415, 1-11, 2002
E.Carlon, P. Lajkó,, H. Rieger and F. Iglói: Disorder induced phases in higher spin antiferromagnetic Heisenberg chains, Phys. Rev. B 69, 144416, 2004
R. Juhász, H. Rieger, and F. Iglói: The random-bond Potts model in the large-q limit, Phys. Rev. E64, 066122, 1-7, 2001
E.Carlon, P. Lajkó, and F. Iglói: Disorder induced cross-over effects at quantum critical points, Phys. Rev. Lett. 87, 277201, 1-4, 2001
F. Igl?i: Exact renormalization of the random transverse-field Ising spin chain in the strongly ordered and strongly disordered Griffiths phases, Phys. Rev. B65, 064416, 1-11, 2002
F. Iglói and L. Turban: First- and second-order phase transitions in scale-free networks, Phy. Rev. E66, 036140, 1-4, 2002
J. Hooyberghs, F. Iglói, and C. Vanderzande: Strong disorder fixed-point in absorbing state phase transitions, Phys. Rev. Lett. 90, 100601, 1-4, 2003
J-Ch. Anglés d`Auriac, F. Iglói, M. Preissmann, and A. Sebő: Optimal cooperation and submodularity for computing Potts partition functions with a large number of states, J. Phys. A35, 6973-83, 2002
R. Juhász and F. Iglói: Percolation in random environment, Phys. Rev. E66, 056113, 1-7, 2002
Y-C. Lin, R. Melin, H. Rieger and F. Iglói: Low-energy fixed points of random Heisenberg models, Phys. Rev. B 68, 024424,1-10, 2003
J-Ch. Anglés d`Auriac, and F. Iglói: Phase transition in the 2d random Potts model in the large-q limit, Phys. Rev. Lett. 90, 190601, 1-4, 2003
M. Pleimling, and F. Iglói: Out-of-equilibrium dynamics at surfaces: Cluster dissolution and non-algebraic correlations, Phys. Rev. Lett. 92, 145701, 2004
M.-T. Mercaldo, J-Ch. Anglés d\'Auriac, and F. Iglói: Disorder induced rounding of the phase transition in the large q-state Potts model, Phys. Rev. E 69, 056112, 2004
J. Hooyberghs, F. Iglói and C. Vanderzande: Absorbing state phase transitions with quenched disorder, Phys. Rev. E 69, 066140, 2004
Y.-C. Lin, H. Rieger and F. Iglói: Antiferromagnetic spin chains with bond alternation and quenched disorder, J. Phys. Soc. Jp. 73, 1602, 2004
M. Pleimling, F. Á. Bagaméry, L. Turban, and F. Iglói: Logarithmic corrections in the two-dimensional Ising model in a random surface field, J. Phys. A 37, 8001-9, 2004
R. Juhász, L. Santen, and F. Iglói: Partially asymmetric exclusion models with quenched disorder, Phys. Rev. Lett. 94, 010601, 2005
M. Pleimling, and F. Iglói: Nonequilibrium critical dynamics in inhomogeneous systems, Phys. Rev. B 71, 094424, 2005
M. T. Mercaldo, J-Ch. Anglés d\'Auriac, and F. Iglói: Disorder driven phase transitions of the large q-state Potts model in 3d, Europhys. Lett. 70, 733, 2005
F. Iglói and C. Monthus: Strong disorder RG approach of random systems, Physics Reports 412, 277-431, 2005
R. Juhász, L. Santen, and F. Iglói: Partially asymmetric zero range process with quenched disorder,, Phys. Rev. E72, 046129, 2005
M. Karsai, R. Juhász, and F. Iglói: Nonequilibrium phase transitions and finite size scaling in weighted scale-free networks, Phys. Rev. E (in print), cond-mat/0504666, 2006
R. Mélin, B. Doucot, and F. Iglói: Strong disorder renormalization group on fractal lattices:Heisenberg models and magnetoresistive effects in tight binding models, Phys. Rev. B 72, 024205, 2005
F.'A. Bagaméry, L. Turban, and F. Iglói: Two-dimensional Ising model with self-dual biaxially correlated disorder, Phys. Rev. B 72, 094202, 2005
L. Környei, M. Pleimling,and F. Iglói: Reentrance during nonequilibrium relaxation, Europhys. Lett. 73, 197, 2006
M. T. Mercaldo, J-Ch. Anglés d\'Auriac, and F. Iglói: Critical and tricritical singularities of the three-dimensional random-bond Potts model for large q, Phys. Rev. E (in print), cond-mat/0511203, 2006
P. Lajkó, E. Carlon, H. Rieger, and F. Iglói: Disorder induced phases in the $S=1$ antiferromagnetic Heisenberg chain, Phys. Rev. B 72, 094205, 2005



Back »