Miscibility gap and possible intrinsic Griffiths phase in Sr(Fe1−xMnx)2As2 crystals grown by transition metal arsenide flux

The crystal structure, magnetic, electronic, and thermal properties of Mn-doped SrFe2As2 crystals have been systematically investigated. A miscibility gap is found in the system from x = 0.4362(4) to 0.9612(9). For < 0.2055(2), single holding tetragonal structure (space group I4/mmm (no. 139)) a continuously enlarged lattice parameter c, followed by phase separation with both trigonal structures up 0.4362(4). Beyond gap, > 0.9612(9) hold P-3m1 164)). Moreover, spin density wave ordering for 0 0.0973(1) suppressed, an abnormal broadened increase temperature 0.2055(2). Eliminating possibility real-space Mn Fe based on results X-ray diffraction, this novel phenomenon can be attributed possible intrinsic Griffiths phase. No any superconducting signals are observed down 2 K whole composition range 1. diagram multi-critical points established accordingly.