Microscopic magnetic properties of itinerant-electron system Hf0.8Ta0.2(Fe1−xcox)2 (x=0–0.09): A Mössbauer study

The compounds of itinerant-electron system Hf0.8Ta0.2(Fe1−xCox)2 (x=0–0.09) were prepared. The crystal structure was examined by X-ray powder diffraction and all indicated a C14-type Laves phase structure. Mössbauer spectra were obtained for all the compounds between 20 and 390 K. The spectra for x=0 clearly showed a transition from antiferromagnetic (AFM) state to ferromagnetic (FM) state at about 110 K and one from paramagnetic state to AFM state at about 350 K. For x=0.03, 0.06 and 0.09, the AFM–FM transition was not observed, and only showed a AFM+FM state below 340, 330, and 320 K, respectively. It indicated that tiny substituted Co atoms would change the magnetic properties of the system, which originated from the disturbed crystal field and corresponding nonzero internal field at 2a site.