Quantum Griffiths effects in itinerant Heisenberg magnets

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 overdamping 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.

6 pages, 1 eps figure, final version as published

References in corpus (3)

• Universal conductance of nanowires near the superconductor-metal quantum transition
• Dissipative dynamics of an extended magnetic nanostructure: Spin necklace in a metallic environment
• Magnetic droplets in a metal close to a ferromagnetic quantum critical point

Cited by in corpus (10)

• Infinite-randomness critical point in the two-dimensional disordered contact process
• Critical behavior and Griffiths effects in the disordered contact process
• Effects of dissipation on a quantum critical point with disorder
• Infinite-randomness quantum critical points induced by dissipation
• Theory of smeared quantum phase transitions
• Percolation quantum phase transitions in diluted magnets
• Thermal expansion and Grueneisen parameter in quantum Griffiths phases
• Absorbing-state phase transitions on percolating lattices
• Ordered droplets in quantum magnets with long-range interactions
• Fluctuation-induced first order transition due to Griffiths anomalies of the Cluster glass phase