Magnon Supersolid and Anomalous Hysteresis in Spin Dimers on a Triangular Lattice

TL;DR

This paper investigates the magnetic phases and hysteresis phenomena in a triangular lattice of spin dimers, revealing magnon supersolid states and unusual hysteresis behavior through cluster mean-field analysis.

Contribution

It introduces the concept of magnon supersolid phases in spin dimer systems and uncovers anomalous hysteresis effects during phase transitions.

Findings

Magnetization plateaus at 1/3 and 2/3 with superlattice patterns.

Occurrence of magnon supersolid phases via BEC of triplons.

Observation of anomalous hysteresis where the system cannot revert to the initial solid state.

Abstract

We study the magnetic phase diagram and hysteresis behavior of weakly coupled spin dimers on a triangular lattice using the cluster mean-field method with cluster-size scaling. We find that the magnetization curve has plateaus at 1/3 and 2/3 of the total magnetization, in which local singlet and triplet states form a superlattice pattern. Moreover, if increasing (decreasing) the magnetic field from the 1/3 (2/3) plateau, the Bose-Einstein condensation (BEC) of triplons occurs on the superlattice background, leading to the transition into magnon supersolid phase. We also find that the first-order transition between these solid states and the standard magnon BEC state exhibits an anomalous hysteresis upon cycling the magnetic field; the transition can occur only from solid to BEC, and the system cannot return to the initial solid state in the reverse process.