Magnetization plateaus as insulator-superfluid transitions in quantum spin systems

TL;DR

This paper investigates how magnetization plateaus in two-dimensional quantum spin systems correspond to insulator-superfluid transitions of magnetic excitations, revealing the role of lattice geometry and interactions.

Contribution

It demonstrates that magnetization plateaus arise from superfluid to insulator transitions of magnetic excitations in various lattice models, highlighting the role of lattice structure and interactions.

Findings

Magnetization plateaus correspond to Mott insulator states of magnetic excitations.

Plateau states exhibit charge density wave order of excitations.

Plateau magnetizations depend on excitation components, interaction range, and lattice geometry.

Abstract

We study the magnetization process in two-dimensional S=1/2 spin systems, to discuss the appearance of a plateau structure. The following three cases are considered: (1) the Heisenberg antiferromagnet and multiple-spin exchange model on the triangular lattice, (2) Shastry-Sutherland type lattice, [which is a possible model for SrCu2(BO3)2,] (3) 1/5-depleted lattice (for CaV4O9). We find in these systems that magnetization plateaus can appear owing to a transition from superfluid to a Mott insulator of magnetic excitations. The plateau states have CDW order of the excitations. The magnetizations of the plateaus depend on components of the magnetic excitations, range of the repulsive interaction, and the geometry of the lattice.