Structural link to precursor effects

Abstract

We investigate the origin of precursor effect associated to magnetic phase transitions in a quasi-one-dimensional system ${\text{Ca}}_{3}{\text{Co}}_{2}{\text{O}}_{6}$, employing extended x-ray absorption fine structure technique. Experimental results reveal unusual changes in the Co-O bond lengths in ${\text{CoO}}_{6}$ units nucleating at a temperature ${T}^{\ensuremath{\star}}$, where the precursor effect occurs. The corresponding Debye-Waller factors representing disorder effect exhibit anomalous evolution across ${T}^{\ensuremath{\star}}$. These results reveal a unique link between the local structural changes and the precursor effect that needs to be considered in the understanding of various phase transitions.