Improving quantum-transition temperatures in BaFe2As2-based crystals by removing local-lattice strain & electronic-structure disorder

Abstract

Quantum materials such as antiferromagnets or superconductors are complex in that chemical, electronic, and spin phenomena at atomic scales can manifest in their collective properties. Although there are some clues for designing such materials, they remain mainly unpredictable. In this work, we find that enhancement of transition temperatures in BaFe2As2-based crystals are caused by removing local-lattice strain and electronic-structure disorder by thermal annealing. While annealing improves Neel-ordering temperature in BaFe2As2 crystal (TN=132 K to 136 K) by removing in-plane electronic defects and overall reduction of a-lattice parameter, it increases superconducting-ordering temperature in optimally cobalt-doped BaFe2As2 crystal (Tc=23 to 25 K) by precipitating-out the cobalt dopants and giving larger overall a-lattice parameter. Although annealing promotes local chemical and electronic uniformity resulting in higher TN in the parent, it results in nanoscale phase separation in the superconductor resulting in lower disparity and strong superconducting band gaps in the dominant crystalline regions, which lead to both higher overall Tc and critical-current-density, Jc.

15 pages, 9 figures

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Cited by in corpus (5)

• Enhanced upper critical field in Co-doped Ba122 superconductors by lattice defect tuning
• Unusual Effects of Be doping in the Iron Based Superconductor FeSe
• Superconductivity with Tc=7 K under pressure for Cu-, and Au-doped BaFe2As2
• Surface reconstruction and charge modulation in BaFe2As2 superconducting film
• Lattice Disorder Effect on Magnetic Ordering of Iron Arsenides