Quantum Critical Behavior of Itinerant Ferromagnets


We investigate the quantum phase transition of itinerant ferromagnets. It is shown that correlation effects in the underlying itinerant electron system lead to singularities in the order parameter field theory that result in an effective long-range interaction between the spin fluctuations. This interaction turns out to be generically antiferromagnetic for clean systems. In disordered systems analogous correlation effects lead to even stronger singularities. The resulting long-range interaction is, however, generically ferromagnetic. We discuss two possibilities for the ferromagnetic quantum phase transition. In clean systems, the transition is generically of first order, as is experimentally observed in MnSi. However, under certain conditions the transition may be continuous with non-mean field critical behavior. In disordered systems, one finds a very rich phase diagram showing first order and continuous phase transitions and several multicritical points.

Meeting Name

LOCALIZATION 1999 International Conference on 'Disorder and Interaction in Transport Phenomena (1999: Jul 29-Aug. 3, Hamburg, Germany)



Keywords and Phrases

Electron energy levels; Ferromagnetic materials; Magnetic fields; Magnetization; Manganese compounds; Mathematical models; Phase diagrams; Quantum theory; Correlation effects; Critical behavior; Order parameter field theory; Quantum magnets; Quantum phase transitions; Spin fluctuations; Order disorder transitions

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Document Type

Article - Conference proceedings

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© 1999 Wiley-VCH Verlag Berlin GmbH, All rights reserved.

Publication Date

01 Jul 1999