Role of anisotropy in the spin-dimer compound BaCuSi2O6

TL;DR

This study investigates how magnetic dipolar interactions induce anisotropy in BaCuSi2O6, revealing a very small symmetry-breaking energy scale that supports Bose Einstein condensation critical scaling near the quantum critical point.

Contribution

It demonstrates that magnetic dipolar interactions are the primary source of anisotropy in BaCuSi2O6 and quantifies the small energy scale of symmetry-breaking.

Findings

Anisotropic terms originate from magnetic dipolar interactions.

Axial symmetry-breaking energy scale is approximately 11 mK.

Bose Einstein condensation critical scaling is observed over an extended temperature range.

Abstract

We present results of magnetisation and electron paramagnetic resonance experiments on the spin-dimer system BaCuSi2O6. Evidence indicates that the origin of anisotropic terms in the spin Hamiltonian is from magnetic dipolar interactions. Axial symmetry-breaking is on a very small energy scale of ~11 mK, confirming Bose Einstein condensation critical scaling over an extended temperature range in the vicinity of the quantum critical point.