Mechanical detwinning device for anisotropic resistivity measurements in samples requiring dismounting for particle irradiation

E I Timmons; M A Tanatar; Yong Liu; Kyuil Cho; T A Lograsso; M Kończykowski; R Prozorov

doi:10.1063/5.0012053

Mechanical detwinning device for anisotropic resistivity measurements in samples requiring dismounting for particle irradiation

Rev Sci Instrum. 2020 Jul 1;91(7):073904. doi: 10.1063/5.0012053.

Authors

E I Timmons¹, M A Tanatar¹, Yong Liu¹, Kyuil Cho¹, T A Lograsso¹, M Kończykowski², R Prozorov¹

Affiliations

¹ Ames Laboratory, USDOE, Ames, Iowa 50011, USA.
² Laboratoire des Solides Irradiés, CEA/DRF/lRAMIS, Ecole Polytechnique, CNRS, Institut Polytechnique de Paris, F-91128 Palaiseau, France.

PMID: 32752837
DOI: 10.1063/5.0012053

Abstract

Uniaxial stress is used to detwin the samples of orthorhombic iron based superconductors to study their intrinsic electronic anisotropy. Here, we describe the development of a new detwinning setup enabling variable-load stress-detwinning with easy sample mounting/dismounting without the need to re-solder the contacts. It enables the systematic study of the anisotropy evolution as a function of an external parameter when the sample is modified between the measurements. In our case, the external parameter is the dose of 2.5 MeV electron irradiation at low temperature. We illustrate the approach by studying resistivity anisotropy in single crystals of Ba_1-xK_xFe₂As₂ at x = 0.25, where the much discussed unusual re-entrance of the tetragonal C₄ phase, C₄ → C₂ → C₄, is observed on cooling. With the described technique, we found a significant anisotropy increase in the C₂ phase after electron irradiation with a dose of 2.35 C/cm².