Wei Ji (季威)1, Xun-Wang Yan (闫循旺)2,1, and Zhong-Yi Lu (卢仲毅)1,*
1Department of Physics, Renmin University of China, Beijing 100872, China
2Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
DOI:10.1103/PhysRevB.83.132504 Publication Date: 13 April 2011
With the proposed Hund’s rule correlation picture, i.e., the fluctuating Fe local moments with the As-bridged antiferromagnetic superexchange interactions, the exceptional collapsed tetragonal phase and related phase transitions observed in CaFe2As2 are well understood. Within the same framework, a pressure-temperature phase diagram is predicted for BaFe2As2 as well, in which a paramagnetic tetragonal structure and a collinear antiferromagnetic orthorhombic structure to nonmagnetic tetragonal structure transitions take place around 4–8 GPa and 10–15 GPa, respectively, and a nonmagnetic tetragonal to a nonmagnetic collapsed tetragonal structure transition takes place over 26 GPa. Our study helps to better understand the complex correlation among crystal structure, magnetism, and electronic structure in pnictides, a precondition to understanding the superconductivity in pnictides.