Mixed valence and metamagnetism in a metal flux grown compound Eu₂Pt₃Si₅

Abstract

A new compound Eu₂Pt₃Si₅ with plate shaped morphology has been grown from excess In flux. The compound crystallizes in the orthorhombic U₂Co₃Si₅ structure type, Ibam space group and the lattice parameters are a=10.007(2) Å, b=11.666(2) Å and c=6.0011(12) Å. The crystal structure of this compound can be conceived as inter-twinned chains of [Pt₂Si₂] and [PtSi₃] tetrahedra connected along [100] direction to give rise to a complex three dimensional [Pt₃Si₅] network. Temperature dependent magnetic susceptibility data suggests that Eu₂Pt₃Si₅ undergoes a strong antiferromagnetic ordering (T_N=19 K) followed by a weak ferromagnetic transition (T_C=5.5 K). The effective magnetic moment/Eu obtained from susceptibility data is 6.78 μ_B accounts mixed valent Eu with almost 85% divalent Eu, which is supported by X-ray absorption near edge spectroscopy. The compound undergoes a metamagnetic transition under applied magnetic field through a probable spin flop mechanism.