Scaling between magnetic and lattice fluctuations in iron-pnictide superconductors

TL;DR

This study uncovers a scaling relation between magnetic and lattice fluctuations in iron-pnictide superconductors, supporting the idea that magnetic fluctuations drive structural transitions crucial for superconductivity.

Contribution

It demonstrates a direct correlation between magnetic and lattice fluctuations using NMR and shear modulus data, revealing the magnetic origin of structural transitions in iron arsenides.

Findings

Scaling relation between NMR and shear modulus data

Evidence for magnetically-driven structural transition

Correlation between magnetic fluctuations and lattice behavior

Abstract

The phase diagram of the iron arsenides is dominated by a magnetic and a structural phase transition, which need to be suppressed in order for superconductivity to appear. The proximity between the two transition temperature lines indicates correlation between these two phases, whose nature remains unsettled. Here, we find a scaling relation between nuclear magnetic resonance (NMR) and shear modulus data in the tetragonal phase of electron-doped $\mathrm{Ba(Fe_{1-x}Co_{x})_{2}As_{2}}$ compounds. Because the former probes the strength of magnetic fluctuations while the latter is sensitive to orthorhombic fluctuations, our results provide strong evidence for a magnetically-driven structural transition.