Study of the pressure on magnetism in spin-ladder superconductor BaFe₂Se₃

Magnetic fluctuations were proposed as important for the pairing glue to the unconventional superconductivity (SC). The proximity of an antiferromagnetic (AFM) ordered has been found ubiquitously, with the majority of the iron-based superconductors exhibiting the same two-dimensional square lattice structural motif. Optimal SC typically appears when the magnetic order is suppressed by applying pressure or doping carriers. Pressure-induced SC in the BaFe₂X₃ (X=Se,S) introduces a quasi-one-dimensional prototype for the studies of the unconventional SC[1,2]. BaFe₂Se₃ shows a block-type AFM transition below T_N = 256 K. By applying pressure, the Mott insulating state is gradually suppressed and displays a SC dome above 10 Gpa similar to the BaFe₂S₃. In this talk, I will present a systematic study of the magnetic and structural properties under hydrostatic pressure in BaFe₂Se₃ using neutron diffraction, x-ray diffraction and muon spin relaxation techniques. These provide the information on how the magnetic phase evolves approaching the SC and compares to the case of BaFe₂S₃.[1]H. Takahashi,et al.,Nat. Mater.(2018).[2]J.J. Ying,et al.,PRB (2017).