Miscibility Gap And Possible Intrinsic Griffiths Phase In Sr(Fe1-Xmnx)(2)As-2 Crystals Grown By Transition Metal Arsenide Flux

The crystal structure, magnetic, electronic, and thermal properties of Sr(Fe1-xMnx)(2)As-2 crystals grown by transition metal arsenide flux have been systematically investigated. A miscibility gap with x ranging from 0.4362(4) to 0.9612(9) is found in the Sr(Fe1-xMnx)(2)As-2 system-for x < 0.4362(4), the phase remains in the parent tetragonal structure [space group I4/mmm (No. 139)], whereas for x > 0.9612(9), the phase exhibits a trigonal structure [space group P-3 m1 (No. 164)]. Based on our observation, the spin density wave order for x < 0.0973(1) is suppressed, followed by an abnormal and broadened increase in the ordering temperature from x = 0.0973(1) to x = 0.2055(2). No real-space phase separation of Mn and Fe was detected for x < 0.2055(2), indicating that the broadened increase in ordering temperature is attributable to a possibly intrinsic Griffiths phase. No superconducting signal was observed down to 2 K in the whole composition range with 0 < x < 1. A phase diagram with multicritical points of Mn-doped SrFe2As2 system is established accordingly.