Structure and magnetic properties of Gd 4(Mn 0.05Sb 0.95) 3

This work studies the structure and magnetic properties of Gd ₄(Mn _0.05Sb _0.95) ₃ with the aim to clarify the role played by the magnetic Mn atom. Upon substitution of Mn for Sb in the parent Gd ₄Sb ₃ compound, it is found that the inverted Th ₃P ₄-like structure has been somewhat expanded. The Curie temperature is increased while magnetic moment, measured in the field of 50 kOe at 200 K, is slightly reduced. The ferromagnetic semiconductor, Gd ₄(Mn _0.05Sb _0.95) ₃, undergoes a ferromagnetic to paramagnetic transition at 270 K. Observed anomalies occur in the magnetization vs. temperature curves measured in a very low magnetic field. They are attributed to magnetic inhomogeneities resulting from a structural modification in Gd ₄(Mn _0.05Sb _0.95) ₃.