Magnetic phase diagrams and magnetization plateaus of the spin-1/2 antiferromagnetic Heisenberg model on square-kagome lattice with three nonequivalent exchange interactions

TL;DR

This study explores the magnetic phase diagrams and magnetization plateaus of a spin-1/2 antiferromagnetic Heisenberg model on a square-kagome lattice with three nonequivalent exchange interactions, revealing a new 2/3 plateau with broken symmetry.

Contribution

It introduces the first investigation of the square-kagome lattice with three nonequivalent bonds, discovering a new magnetization plateau not seen in simpler models.

Findings

Identified a new 2/3 magnetization plateau with broken four-fold rotational symmetry.

Confirmed existing 1/3 and 2/3 plateaus in the model with two equivalent bonds.

Proposed experimental search for these plateaus in related materials.

Abstract

Magnetization plateaus in quantum spin systems emerges in two-dimensional frustrated systems such as kagome lattice. The spin-1/2 antiferromagnetic Heisenberg model on square-kagome lattice is also appropriate for the study of magnetization plateau. Motivated by recent experimental finding of such a square-kagome lattice with nonequivalent three bonds, we investigate the phase diagrams and magnetization plateaus of the lattice by the exact diagonalization method. In addition to previously reported the 1/3 and 2/3 plateaus in the model with two equivalent bonds, we find a new 2/3 plateau whose magnetic structure is characterized by spontaneously broken four-fold rotational symmetry. The plateau appears only in the case of three nonequivalent bonds. We propose the possibility of finding plateaus including the new one.