Effect of biaxial strain on the phase transitions of Ca(Fe1-xCox)2As2

TL;DR

This study demonstrates that biaxial strain can induce magneto-structural transitions and superconductivity in Ca(Fe1-xCox)2As2, providing a new way to control its phase behavior through physical strain.

Contribution

It introduces a method of applying biaxial strain via substrate bonding to tune phase transitions in Ca(Fe1-xCox)2As2, revealing new pathways for controlling its properties.

Findings

Biaxial strain induces magneto-structural phase transitions.

Strain can induce superconductivity in non-superconducting samples.

Transition behavior is gradual under strain, unlike pressure or stress.

Abstract

We study the effect of applied strain as a physical control parameter for the phase transitions of Ca(Fe1-xCox)2As2 using resistivity, magnetization, x-ray diffraction and 57Fe M\"ossbauer spectroscopy. Biaxial strain, namely compression of the basal plane of the tetragonal unit cell, is created through firm bonding of samples to a rigid substrate, via differential thermal expansion. This strain is shown to induce a magneto-structural phase transition in originally paramagnetic samples; and superconductivity in previously non-superconducting ones. The magneto-structural transition is gradual as a consequence of using strain instead of pressure or stress as a tuning parameter.