At the beginning of 2020, to celebrate the 50th anniversary of Physical Review B, the editors of the journal elaborately selected 7 Milestone Papers that have made lasting contributions to condensed matter physics and materials physics from, according to incomplete statistics, over 190,000 published articles. Among the 7 selected papers, "Superconductivity in the iron selenide K_xFe₂Se₂ " (2010) by the research team led by Chen Xiaolong of the Institute of Physics (IOP) of the Chinese Academy of Sciences (CAS), is the only one from China. Guo Jiangang of IOP is the first author of this paper.

The Chen Xiaolong research team took the FeSe layer as the structure unit, intercalated the charge-carrier layer while adjusting its structure order with Potassium Kalium, and finally discovered K_xFe₂Se₂, the first alkali metal iron selenide superconductor, whose critical temperature is 30K. Several research groups at home and abroad have successively proved that the Fermi surface configuration of K_xFe₂Se₂ is completely different from that of iron-arsenide high-temperature superconductors. The result overturns the mainstream view that Fermi surface nesting induces superconductivity and triggers a new upsurge in superconductivity research. This research result has guided a new direction for superconducting research and piloted over 300 research teams from over 30 countries to carry out follow-up research. It has been listed as the 1st and 7th hottest research in physics on Research Fronts 2013 and Research Fronts 2014 published by Thomson Reuters, respectively. In addition, it is recognized by Chinese and foreign peers as the new type of iron-based high-temperature superconductor first discovered by Chinese scientists in parallel with iron-arsenide superconductors. This work has exerted sustained influence. Researchers at home and abroad have achieved several important results on this basis. In addition, Chen Xiaolong research team also discovered A_x (NH3) _yFe₂Se₂ (A = Li, Na, Ca, Sr, Ba, Eu, Yb) series superconductors by using metal and ammonia molecules to coordinate the regulation sequence, successfully raising its critical temperature to 46K, which is higher than McMillan limit. See the link at the end of the article for details.

Physical Review B is a peer-reviewed, scientific journal specializing in condensed matter and materials physics established by the American Physical Society (APS) in 1970.