Local defect in a magnet with long-range interactions

Abstract

We investigate a single defect coupling to the square of the order parameter in a nearly critical magnet with long-range spatial interactions of the form $r^{-(d+\sigma )}$, focusing on magnetic droplets nucleated at the defect while the bulk system is in the paramagnetic phase. Because of the long-range interaction, the droplet develops a power-law tail which is energetically unfavorable. However, as long as $\sigma >0$, the tail contribution to the droplet free energy is subleading in the limit of large droplets; and the free energy becomes identical to the case of short-range interactions. We also study the droplet quantum dynamics with and without dissipation; and we discuss the consequences of our results for defects in itinerant quantum ferromagnets.

8 pages, 5 eps figures, final version, as published

References in corpus (1)

• Absence of conventional quantum phase transitions in itinerant systems with disorder

Cited by in corpus (1)

• Ordered droplets in quantum magnets with long-range interactions