Effect of tensile stress on the in-plane resistivity anisotropy in BaFe2As2

TL;DR

This study investigates how uniaxial tensile stress affects the structural and resistivity properties of BaFe2As2, revealing strain-induced anisotropy and differences from SrFe2As2, supported by experimental and phenomenological modeling.

Contribution

It provides new insights into strain effects on structural transitions and resistivity anisotropy in BaFe2As2, highlighting differences from related compounds.

Findings

Strain induces structural distortion above the magnetic transition.

Resistivity anisotropy is affected by strain and structural smearing.

Differences in structural response explain resistivity anisotropy above transition.

Abstract

The effect of uniaxial tensile stress and the resultant strain on the structural/magnetic transition in the parent compound of the iron arsenide superconductor, BaFe$_2$As$_2$, is characterized by temperature-dependent electrical resistivity, x-ray diffraction and quantitative polarized light imaging. We show that strain induces a measurable uniaxial structural distortion above the first-order magnetic transition and significantly smears the structural transition. This response is different from that found in another parent compound, SrFe$_2$As$_2$, where the coupled structural and magnetic transitions are strongly first order. This difference in the structural responses explains the in-plain resistivity anisotropy above the transition in BaFe$_2$As$_2$. This conclusion is supported by the Ginzburg-Landau - type phenomenological model for the effect of the uniaxial strain on the resistivity anisotropy.