Phase Transitions of the Bilayered Spin-S Heisenberg Model and Its Extension to Fractional Dimensions

TL;DR

This paper investigates the phase transitions in a bilayered spin-$S$ Heisenberg model, revealing how interplane coupling affects magnetic order and exploring the model's behavior in fractional dimensions.

Contribution

It extends the analysis of the bilayered spin-$S$ Heisenberg model to fractional dimensions and compares transition types across different spin values.

Findings

Interplane coupling stabilizes then destroys antiferromagnetic order.

Transition type depends on spin magnitude: continuous for small $S$, first order for large $S$.

Phase diagram in fractional dimensions is discussed.

Abstract

We study the ground state and the phase transitions of the bilayered spin-$S$ antiferromagnetic Heisenberg model using the Schwinger boson mean field theory. The interplane coupling initially stabilizes but eventually destroys the long-range antiferromagnetic order. The transition to the disordered state is continuous for small $S$, and first order for large $S$. The latter is consistent with an argument based on the spin wave theory. The phase diagram and phase transitions in corresponding model in fractional dimensions are also discussed.