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- Title
Optical anisotropy in optimally doped iron-based superconductor.
- Authors
Pal, Anirban; Chinotti, Manuel; Chu, Jiun-Haw; Kuo, Hseuh-Hui; Fisher, Ian Randal; Degiorgi, Leonardo
- Abstract
The divergent nematic susceptibility, obeying a simple Curie-Weiss power law over a large temperature interval, is empirically found to be a ubiquitous signature in several iron-based materials across their doping-temperature phase diagram. The composition at which the associated Weiss temperature extrapolates to zero is found to be close to optimal doping, boosting the debate to what extent nematic fluctuations contribute to the pairing-mechanism and generally affect the electronic structure of iron-based superconductors. Here, we offer a comprehensive optical investigation of the optimally hole-doped Ba0.6K0.4Fe2As2 over a broad spectral range, as a function of temperature and of tunable applied stress, which acts as an external symmetry breaking field. We show that the stress-induced optical anisotropy in the infrared spectral range is reversible upon sweeping the applied stress and occurs only below the superconducting transition temperature. These findings demonstrate that there is a large electronic nematicity at optimal doping which extends right under the superconducting dome. Fe-based superconductors: nematicity probed by optical measurements Optical measurements on an Fe-based superconductor reveal a large electronic nematicity at optimal doping, which might influence the emergence of superconductivity. A divergent nematic susceptibility is observed in several Fe-based superconductors across the doping–temperature phase diagram, and might enhance the pairing interaction. To investigate the influence of the nematic fluctuations on the electronic properties, Leonardo Degiorgi from ETH Zürich in Switzerland and colleagues from an international collaboration applied a tunable stress (used as a symmetry-breaking field) on optimally doped Ba1-xKxFe2As2, studying its optical response as a function of temperature and stress. They found an unprecedented stress-induced optical anisotropy below the superconductive critical temperature, demonstrating that the electronic structure is very susceptible to symmetry-breaking stress. This might give insight on the relationship between nematic fluctuations and unconventional superconductivity.
- Subjects
ANISOTROPY; SUPERCONDUCTORS; CURIE-Weiss law; SUPERCONDUCTIVITY; TRANSITION temperature
- Publication
NPJ Quantum Materials, 2019, Vol 4, Issue 1, pN.PAG
- ISSN
2397-4648
- Publication type
Article
- DOI
10.1038/s41535-018-0140-1