Experimental Evidences for Static Charge Density Waves in Iron Oxy-pnictides

TL;DR

This study provides experimental evidence of static charge density waves in Mn-substituted LaFeAsO, revealing a charge-driven density wave instability associated with structural modulation in Fe-based superconductors.

Contribution

It demonstrates the presence of incommensurate charge density wave modulations in Mn-doped LaFeAsO using high-resolution diffraction and microscopy techniques.

Findings

Incommensurate structural distortion depends on Mn content

Charge density wave likely causes the observed modulation

Density wave ordering is charge-driven in these materials

Abstract

In this Letter we report high-resolution synchrotron X-ray powder diffraction and transmission electron microscope analysis of Mn-substituted LaFeAsO samples, demonstrating that a static incommensurate modulated structure develops across the low-temperature orthorhombic phase, whose modulation wave-vector depends on the Mn content. The incommensurate structural distortion is likely originating from a charge-density-wave instability, a periodic modulation of the density of conduction electrons associated with a modulation of the atomic positions. Our results add a new component in the physics of Fe-based superconductors, indicating that the density wave ordering is charge-driven.