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报告摘要：
Connections among crystal chemistry, disorder and critical temperature Tc are at the forefront of superconductivity. In Fe-based superconductors Tc correlates with the average anion height above the Fe plane. By synthesizing FeSe₁₋ₓSₓ (0 ≤ x ≤ 1) single crystal alloys with atomic defects we find that their Tc is not correlated with the anion height. Instead, changes in Tc(x) and tetragonal-to-orthorombic (nematic) transition Ts(x) on cooling are correlated with Bragg plane and Fe vibrations disorder in direction orthogonal to Fe planes and thereby induced scattering rates (1/τ)(x). The disorder stems from deformed Fe(Se,S)4 tetrahedra with different Fe-Se and Fe-S bond distances. Moreover, high-temperature metallic resistivity in the region of strong disorder exceeds Mott limit and is an example of the violation of Matthiesen's rule and Mooij law which is known to be a dominant when adding moderate disorder past the Drude/Matthiassen's regime in all materials. Scattering mechanism of Mott limit-exceeding resistivity arises from strong Se/S atom disorder in tetrahedral surrounding of Fe. High sensitivity of FeSe to local symmetry breaking is further manifested in a strain-tuned fluctuation-enhanced electron phonon coupling in FeSe even in the absence of chemical disorder. Observations point to intricate connection between nanostructure details and unconventional scattering mechanism, possibly related to charge-nematic or magnetic spin fluctuations.

[1] Aifeng Wang et al., Inorg. Chem. 61, 11036 (2022).
[2] Aifeng Wang et al., Nano Lett. 22, 6900 (2022).
[3] Yu Liu et al., Nanoscale Horizons 10, 59 (2023).
[4] J. Blagojevic et al., arXiv:2602.20756 (Phys. Rev. B in press)

报告人简介：
Cedomir Petrovic is currently a professor at Shanghai Advanced Research in Physical Sciences since 2023. He is also an Adjunct Distinguished Fellow, Tsung-Dao Lee Institute, Shanghai Jiao Tong University. He received Ph.D. in Physics in 2000 from Florida State University, NHMFL Tallahassee. From 2002 to 2023, he was leading the exploratory materials/crystals growth and characterization lab in the Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory (BNL). Prof. Petrovic has received a number of awards for his work in new materials exploration, including “Marko Jaric” Serbian Physics award 2009, Humboldt Fellowship for Experienced Researchers 2011-2014, Serbian Academy of Sciences and Arts – Foreign Associate Member (2015-present), APS Fellow 2016, BNL Science and Technology Award (2022), and Oriental Pearl Talent Award (2024).

邀请人：孙培杰 研究员

联系人：魏佳 secuf_wj@iphy.ac.cn