  Here, we report the synthesis and physical properties of Co2FeGe (CFG)
Heusler alloy (HA) nanoparticles (NPs). The NPs of size 23 nm are prepared
using the co-precipitation method. X-ray and selected area electron diffraction
patterns have confirmed the cubic Heusler phase of the NPs with the
A2-disorder. These NPs are soft ferromagnetic, and exhibit a high saturation
magnetization (Ms) along with a very high Curie temperature (Tc) of 1060 K. The
observed Tc value matches closely with the theoretically calculated one
following a model provided by Wurmehl et al. [1]. The high Ms and Tc make the
present system a potential candidate for magnetically activated nano-devices
working at high temperatures. The near-integral value 5.9 mehoB/f.u. of Ms at
low temperatures indicates that the half-metallic ferromagnetism is preserved
even in the particles even on the 20 nm length scale. Additionally, we have
facilitated the existing HA-NP preparation method, which can be used in
synthesizing other HA-NPs. The first-principles density functional theory
computations complement the experimental results.
