Quantum magnetism of perfect spin tetrahedra in Co$_{4}$B$_{6}$O$_{13}$

TL;DR

This study investigates the quantum magnetic properties of perfect spin tetrahedra in Co$_{4}$B$_{6}$O$_{13}$, revealing quantized spin states and complex singlet ground states through experimental measurements and theoretical calculations.

Contribution

It provides a detailed experimental and theoretical analysis of the quantum magnetism in a high-symmetry spin tetrahedral system, highlighting the role of anisotropies and interactions.

Findings

High-field magnetization shows periodic undulation indicating spin quantization.

Magnetic susceptibility and specific heat suggest a singlet-rich ground state.

Theoretical calculations accurately reproduce experimental results.

Abstract

Co$_{4}$B$_{6}$O$_{13}$ contains undistorted tetrahedral clusters of magnetic Co$^{2+}$ ions. The high-field magnetization of this magnet exhibits a periodic undulation indicating quantization of the total spin number per cluster. Measurements of magnetic susceptibility and specific heat reveal that the ground state is composed of several different singlet states, reflecting the high symmetry of the spin tetrahedron. An exact diagonalization calculation taking account of single-ion type anisotropies and Dzyaloshinsky-Moriya interactions reproduces the expretimental results very well.