Ordered droplets in quantum magnets with long-range interactions

Abstract

A defect coupling to the square of the order parameter in a nearly quantum-critical magnet can nucleate an ordered droplet while the bulk system is in the paramagnetic phase. We study the influence of long-range spatial interactions of the form $r^{-(d+\sigma )}$ on the droplet formation. To this end, we solve a Landau-Ginzburg-Wilson free energy in saddle point approximation. The long-range interaction causes the droplet to develop an energetically unfavorable power-law tail. However, for $\sigma >0$, the free energy contribution of this tail is subleading in the limit of large droplets; and the droplet formation is controlled by the defect bulk. Thus, for large defects, long-range interactions do not hinder the formation of droplets.

2 pages, 3 eps figures, final version as published

References in corpus (8)

• Rare region effects at classical, quantum, and non-equilibrium phase transitions
• Influence of Generic Scale Invariance on Classical and Quantum Phase Transitions
• Non-Fermi Liquid Behavior in U and Ce Alloys: Criticality, Disorder, Dissipation, and Griffiths-McCoy singularities
• Disorder-induced rounding of certain quantum phase transitions
• Quantum Griffiths effects in itinerant Heisenberg magnets
• Local Defect in Metallic Quantum Critical Systems
• Breakdown of Landau-Ginzburg-Wilson theory for certain quantum phase transitions
• Local defect in a magnet with long-range interactions