Evolution of magnetism in Hf–Fe metallic glasses

We have measured the magnetization and ac susceptibility of Hf100−xFex (20 ≤ x ≤ 90) metallic glasses in the temperature range 1.5–300 K and magnetic fields up to 5.5 T. For 25 ≤ x ≤ 43 the magnetic susceptibility increases rapidly with x due to the onset of magnetic correlations in the vicinity of the transition into the ferromagnetic state, xc∼50. However, for 35 ≤ x ≤ 43 the alloys consist of self-assembled magnetic nanoclusters embedded within a paramagnetic matrix. These clusters grow rapidly with increasing x. Thus, Hf–Fe glassy alloys evolve from the superconducting through superparamagnetic to ferromagnetic state with increasing Fe-content. The results are compared with those for Zr–Fe glassy alloys.

► Magnetic phase diagram of Hf100−xFex (20 ≤ x ≤ 90) glassy alloys is established.
► For 35 ≤ x ≤ 43 nanosize magnetic clusters self-assemble within paramagnetic host.
► Size of these clusters is simply controlled by Fe content.