Magnetic and Structural Properties of Melt-Spun Co-Ge Ribbons*

The Co-Ge materials is a key subsystem of Heusler alloys and have attracted much interest because they play an important role in the field of integrated circuits [1, 2]. In this work, we have investigated the magnetic and structural properties of Co-Ge melt-spun ribbons in an attempt to understand better the behavior of our Co₂Ge nanoparticles prepared by the cluster-beam deposition technique. Melt-spun ribbons with different compositions and different wheel speeds were prepared. Our data showed that small variations in the Co content and wheel speed lead to different structures and magnetic properties. The ribbons with 65% Co composition are ferromagnetic at room temperature with Curie temperatures larger than 800 K in contrast to previous reports that claimed to be ferromagnetic at cryogenic temperatures [3]. The contradiction with the literature could be attributed to the difference in grain size in the ribbons and can explain the effect of size on the magnetic properties of our nanoparticles.

[1] Y. Xin et al., Intermetallics, 2017, 80, 10-15.
[2] Chun-I Tsai et al., ACS Nano 2011, 5, 9552−9558.
[3] G. F. Zhou and H. Bakker, Phys. Rev. B, 1993, 48, 13383.