Abstract
The tetragonal-to-orthorhombic phase transition at , which precedes the antiferromagnetic phase transition at in many iron-based superconductors, is considered one of the manifestations of electronic nematic order. By constructing temperature-pressure phase diagrams of pure and Co-doped , we study the relation of and under pressure . Our data disclose two qualitatively different regimes in which either increases or decreases with . We provide experimental evidence that the transition between the two regimes may be associated with sudden changes of the Fermi surface topology. Therefore, our results not only support the electronic origin of the structural order, but also emphasize the importance of details of the Fermi surface for the evolution of nematic order under pressure.
12 More- Received 2 July 2019
- Revised 30 July 2019
DOI:https://doi.org/10.1103/PhysRevB.100.064512
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