Competition between orthorhombic and re-entrant tetragonal phases in underdoped Ba1–xKxFe2As2 probed by the response to controlled disorder

• Published in: Physical review. B 2019-02, Vol.99 (5)
• Main Authors: Timmons, E. I., Tanatar, M. A., Willa, K., Teknowijoyo, S., Cho, Kyuil, Kończykowski, M., Cavani, O., Liu, Yong, Lograsso, T. A., Welp, U., Prozorov, R.
• Format: Article
• Language: English
• Subjects: CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
• ISSN: 2469-9950; 2469-9969
• DOI: 10.1103/PhysRevB.99.054518

Low-temperature (22 K) irradiation with 2.5-MeV electrons, creating point defects affecting elastic scattering, was used to study the competition between stripe C2 and tetragonal C4 antiferromagnetic phases which exist in a narrow doping range around x = 0.25 in hole-doped Ba1–xKxFe2As2. In nearby compositions outside of this range, at x = 0.22 and x = 0.19, the temperatures of both the concomitant orthorhombic/stripe antiferromagnetic transition TC2 and the superconducting transition Tc are monotonically suppressed by added disorder at similar rates of about 0.1 K/μΩcm, as revealed through using resistivity variation as an intrinsic measure of scattering rate. In a stark contrast, a rapid suppression of the C4 phase at the rate of 0.24 K/μΩcm is found at x = 0.25. Moreover, this suppression of the C4 phase is accompanied by unusual disorder-induced stabilization of the C2 phase, determined by resistivity and specific heat measurements. Furthermore, the rate of the C4 phase suppression is notably higher than the suppression rate of the spin-vortex phase in the Ni-doped CaKFe4As4 (0.16 K/μΩcm).