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Critical and off‐critical singularities in disordered quantum magnets
Author(s) -
Rieger H.
Publication year - 1998
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/(sici)1521-3889(199811)7:5/6<564::aid-andp564>3.0.co;2-u
Subject(s) - percolation (cognitive psychology) , gravitational singularity , physics , quantum phase transition , condensed matter physics , quantum , phase transition , quantum critical point , critical phenomena , uncorrelated , quantum phases , quantum fluctuation , statistical physics , quantum mechanics , theoretical physics , mathematics , statistics , neuroscience , biology
We study disordered systems at and near quantum phase transitions, which are transitions at zero temperature that are driven by quantum instead of thermal fluctuations. Special emphasis is put on the so‐called Griffiths‐McCoy regions surrounding these transitions in magnetic systems, where various susceptibilities are found to be divergent for T → 0 without the system being critical. We present a phenomenological picture for uncorrelated and weakly or strongly correlated disorder and check it for various models. In higher dimensions the phenomena seem to be connected to a percolation transition.