Ferromagnetic feature from Mn near room temperature in the fine particles of GdMn2Ge2 and TbMn2Ge2

TL;DR

This study shows that fine particles of GdMn2Ge2 and TbMn2Ge2 exhibit a transition from antiferromagnetism to ferromagnetism in Mn sub-lattice near room temperature, influenced by particle size and defects.

Contribution

It reveals that particle size and defects can alter magnetic ordering in GdMn2Ge2 and TbMn2Ge2, challenging the traditional view of Mn-Mn distance as the key factor.

Findings

Weakening of antiferromagnetism in fine particles

Emergence of ferromagnetism near room temperature

Size and defects influence magnetic behavior

Abstract

The magnetization behaviors of GdMn2Ge2 and TbMn2Ge2 in the bulk and in the fine particles obtained by high-energy ball-milling are compared. Pronounced modificayions in the spontaneous, remnent and high-field magnetization in the fine particle form, attributable to Mn are observed. The results indicate that the antiferromagnetism of Mn sub-lattice known for the bulk form in the range 100-300 K gets weakened in favor of ferromagnetism in the fine particles. On the basis of this observation, we infer that there are other factors like size (and possibly defects) also play a role to decide the exact nature of magnetic ordering of Mn in this ternary family of compounds, contrasting the traditionally held view that the basal plane Mn-Mn distance is the crucial controlling parameter.