Re-entrant spin-flop transition in nanomagnets

TL;DR

This paper investigates a re-entrant spin-flop transition in nanomagnets with odd-numbered antiferromagnetic chains, revealing a continuous, second-order transition influenced by anisotropy and magnetic field, robust against quantum fluctuations.

Contribution

It introduces the concept of a re-entrant spin-flop transition in nanomagnets with anisotropy, expanding understanding of magnetic phase transitions in finite systems.

Findings

Re-entrant transition occurs with both weak and strong magnetic fields.

Transitions are second order and continuous.

Robustness against quantum fluctuations suggests experimental observability.

Abstract

Antiferromagnetic chains with an odd number of spins are known to undergo a transition from an antiparallel to a spin-flop configuration when subjected to an increasing magnetic field. We show that in the presence of an anisotropy favoring alignment perpendicular to the field, the spin-flop state appears for both weak and strong field, the antiparallel state appearing for intermediate fields. Both transitions are second order, the configuration varying continuously with the field intensity. Such re-entrant transition is robust with respect to quantum fluctuations and it might be observed in different types of nanomagnets.