联系人：罗会仟 研究员 （hqluo@iphy.ac.cn）

报告摘要：

In doped Hund's metals, such as the iron-based superconductors (FeSCs), effects like charge doping and chemical pressure are often considered the dominant factors. Partial chemical substitution, however, inevitably introduces disorder. For relatively well explored members of the FeSCs, namely the 122 BaFe₂As₂, a puzzling asymmetry is observed: in the case of transition metal substitution, a superconducting state is not stabilized in the putative hole-doped side of the phase diagram. Moreover, For a significant composition range, the suppression of the antiferromagnetic ordered phase in Cr-and Mn-substituted BaFe₂As₂ (respectively CrBFA and MnBFA) coincides as a function of Cr/Mn content. We carried out a detailed characterization of the electronic structure and spin excitations [1-4] of CrBFA and MnBFA. Our work encompasses ARPES and RIXS experimental probes and supporting DFT+DMFT calculations of the ARPES spectral function plus theoretical modeling of the spin excitations. Our experimental findings and analysis supports that in the cases of CrBFA and MnBFA disorder dominates over charge doping and is the tuning knob of their phase diagram. We speculate whether the role of disorder in the FeSCs deserves further attention.

[1] F..A. Garcia, et al, Phy. Rev.B, B 99 (11), 115118 (2019)
[2] M.R. Cantarino, et al, Phys. Rev. B, 108 (24), 245124 (2023)
[3] M.R. Cantarino, et al, Sci Post Physics, 17 (5), 141 (2024)
[4] M.R. Cantarino, et al, Phys. Rev. Res. - Letters 8 (1), L012028 (2026)

报告人简介：

Fernando Garcia is an Associate Professor at the University of Sao Paulo, Brazil since 2014. In 2022, he was promoted to the rank of associate professor. Since 2025 he is serving as the deputy head for the department of applied physics, overseeing the department strategic planning for the next 5 years. His PhD is from the State University of Campinas (Unicamp) and had postdoctoral experiences at the Max Planck CPFS (Dresden, Germany), Unicamp and, more recently, at the Ames National Laboratory (Ames, US), during a two-year sabbatical period. Prof. Garcia has experience in condensed matter physics, and is specialized in RIXS and ARPES spectroscopy of correlated materials. His recent work is about Iron-based superconductors, Ce-based Kondo lattices and transition metal dichalcogenides.

Email: ifuspfgarcia@usp.br

Website: https://sites.google.com/site/ferton/home?authuser=0