Two types of adjacent dimer layers in the low temperature phase of BaCuSi2O6

TL;DR

This study reveals that BaCuSi2O6 exhibits two distinct types of Cu-Cu dimer layers at low temperatures, with structural differences confirmed by diffraction techniques, impacting magnetic interactions.

Contribution

It provides detailed structural characterization of BaCuSi2O6's low-temperature phase, identifying two types of dimer layers and their influence on magnetic exchange paths.

Findings

Identification of two types of Cu-Cu dimer layers.

Structural differences influence magnetic exchange interactions.

Results support previous NMR and neutron scattering interpretations.

Abstract

The low-temperature crystal structure of BaCuSi2O6 has been investigated with high-resolution synchrotron x-ray and neutron powder diffraction techniques and has been found to be on average (ignoring the incommensurate modulation) orthorhombic, with the most probable space group Ibam. The Cu-Cu dimers in this material are forming two types of layers with distinctly different interatomic distances. Subtle changes also modify the partially frustrated interlayer Cu-Cu exchange paths. The present results corroborate the interpretation of low-temperature nuclear magnetic resonance and inelastic neutron scattering data in terms of distinct dimer layers.