Singlet Ground State and Spin Gap in S=1/2 Kagome Antiferromagnet Rb$_2$Cu$_3$SnF$_{12}$

TL;DR

This study reveals that Rb$_2$Cu$_3$SnF$_{12}$ exhibits a singlet ground state with a spin gap, confirming theoretical predictions for a modified S=1/2 Kagome antiferromagnet through experimental and computational analysis.

Contribution

The paper provides experimental evidence of a disordered singlet ground state with a spin gap in a modified Kagome antiferromagnet, supported by exact diagonalization analysis.

Findings

Ground state is a disordered singlet with a spin gap.

Magnetic susceptibility and magnetization measurements support the spin gap.

Exact diagonalization helps evaluate exchange interactions.

Abstract

We investigated the crystal structure of Rb$_2$Cu$_3$SnF$_{12}$ and its magnetic properties using single crystals. This compound is composed of Kagome layers of corner-sharing CuF$_{6}$ octahedra with a 2a x 2a enlarged cell as compared with the proper Kagome layer. Rb$_2$Cu$_3$SnF$_{12}$ is magnetically described as an $S$=1/2 modified Kagome antiferromagnet with four kinds of neighboring exchange interaction. From magnetic susceptibility and high-field magnetization measurements, it was found that the ground state is a disordered singlet with the spin gap, as predicted from a recent theory. Exact diagonalization for a 12-site Kagome cluster was performed to analyze the magnetic susceptibility, and individual exchange interactions were evaluated.