High-Pressure Single-Crystal Neutron Scattering Study of Magnetic and Fe Vacancy Orders in (Tl,Rb) ₂ Fe ₄ Se ₅ Superconductor

Abstract

The magnetic and iron vacancy orders in superconducting (Tl,Rb)2Fe4Se5\nsingle-crystals are investigated by using a high-pressure neutron diffraction\ntechnique. Similar to the temperature effect, the block antiferromagnetic order\ngradually decreases upon increasing pressure while the Fe vacancy\nsuperstructural order remains intact before its precipitous disappearance at\nthe critical pressure Pc = 8.3 GPa. Combined with previously determined Pc for\nsuperconductivity, our phase diagram under pressure reveals the concurrence of\nthe block AFM order, the iron vacancy order and superconductivity for the 245\nsuperconductor. A synthesis of current experimental data in a coherent physical\npicture is attempted.\n