In this paper, the
room-temperature magnet Gd6FeBi2 was comprehensively
characterized by means of temperature-dependent
single-crystal X-ray diffraction, magnetization measurements, and
experimental electron density and electronic structure computations.
This work explores the electron-spin effects of Fe on this structure
and suggests that Gd6FeBi2 shows structural
features and exchange interactions, which are clearly distinguishable
from other analogues, including the solid solutions Dy6–x
Gd
x
FeBi2 (0
≤ x ≤ 5). The unique traits of Gd6FeBi2 and its derivatives encompass abnormal variations
of lattice parameters with the temperature, as well as the presence
of multiple magnetic transitions of complex nature. Based on the comprehensive
analyses, it can be suggested that the unique magnetic response in
this material is the result from tunable Fe spin states, which are
coupled with strong Gd 5d–Fe 3d interactions, which differ
from other members of this large, structural family. In the ground
state, according to density functional theory calculations, the Fe
atom carries two net electrons, whose spins are coupled in an antiparallel
fashion to the spins of the Gd electrons. Near the Curie temperature,
the Fe net moment is reduced intermittently, coupled with a multiple
of magnetic transitions. The magnetic correlations are manifested
in unexpected variations of the lattice parameters as a function of
temperature, suggesting spin–lattice interactions. This study
emphasizes the important role of Gd 5d electrons in tuning Fe 3d-based
magnetic contribution, which enables better understanding on the spin
coupling in other related compounds and sheds light on the development
of new magnetic and spintronic compounds.