# Structure and Spin-Glass Magnetism of the Fe1.5Ni1.5Ga4 Metallic Alloy

## TL;DR

A new metallic alloy, Fe1.5Ni1.5Ga4, was discovered with a unique cubic structure and spin-glass magnetic behavior below 9 K.

## Contribution

The discovery of a new phase in the Fe–Ni–Ga system with spin-glass magnetism and a disordered cubic structure.

## Key findings

- Fe1.5Ni1.5Ga4 forms a single-phase cubic material with the Ia3̅d structure.
- The alloy exhibits spin-glass behavior below 9 K due to random magnetic moment ordering.
- A chiral structural model I4132 cannot be ruled out based on current crystallographic data.

## Abstract

The Ga-rich region of the Fe–Ni–Ga ternary
system
was investigated, by exploring a line of compositions Fe
x
Ni3–x
Ga4, with 0.5 ≤ x ≤ 2.5. The single-phase
cubic material was found only at the composition Fe1.5Ni1.5Ga4 and its immediate vicinity, representing
a new phase in the Fe–Ni–Ga diagram. The homogeneity
range of this phase was estimated by additionally exploring a set
of compositions Fe
x
Ni
y
Ga
z
around the central composition
Fe1.5Ni1.5Ga4. The structural model
was constructed based on the structure of the binary Ni3Ga4 parent phase, which crystallizes in the cubic Ia3̅d space group. We have considered
that by substituting Fe for Ni, the Ia3̅d structure is preserved, with the Fe and Ni being statistically
distributed at their 48g Wyckoff site. The possibility
of a symmetry-reduced chiral structural model I4132 driven by chemical ordering of Fe and Ni cannot be entirely
ruled out on the basis of the crystallographic study. The magnetic
study of the Fe1.5Ni1.5Ga4 phase
has revealed that the material forms a spin glass phase below the
spin freezing temperature T
f ≈
9 K. Since the spin glass ordering of the Fe and Ni magnetic moments
is compatible with their random distribution, the magnetic study supports
the disordered cubic Ia3̅d model.