Quantum Griffiths effects in itinerant Heisenberg magnets

Thomas Vojta and Jörg Schmalian
Phys. Rev. B 72, 045438 – Published 15 July 2005

Abstract

We study the influence of quenched disorder on quantum phase transitions in itinerant magnets with Heisenberg spin symmetry, paying particular attention to rare disorder fluctuations. In contrast to the Ising case where the Landau damping of the spin fluctuations suppresses the tunneling of the rare regions, the Heisenberg system displays strong power-law quantum Griffiths singularities in the vicinity of the quantum critical point. We discuss these phenomena based on general scaling arguments, and we illustrate them by an explicit calculation for O(N) spin symmetry in the large-N limit. We also discuss broad implications for the classification of quantum phase transitions in the presence of quenched disorder.

    • Received 8 March 2005

    DOI:https://doi.org/10.1103/PhysRevB.72.045438

    ©2005 American Physical Society

    Authors & Affiliations

    Thomas Vojta

    • Department of Physics, University of Missouri-Rolla, Rolla, Missouri 65409, USA

    Jörg Schmalian

    • Department of Physics and Astronomy and Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA

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    Issue

    Vol. 72, Iss. 4 — 15 July 2005

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