Rotational spin-glass properties of nearly ferromagnetic Tb0.15Y0.85Zn

For this cubic pseudobinary compound, the bifurcation of the magnetization (M) vs temperature for warming and cooling in low fields (after zero-field cooling) indicates a spin-glass freezing point (Tg) of ∼20 K. Isotherms of M vs cooling field show zero spontaneous moments down to 4.2 K but an initial susceptibility that almost diverges below Tg . From rotational measurements of M as a vector in a fixed field (H) at 4.2 K, the anisotropy field produced by field cooling (HK) is found to turn rigidly with the sample for H below ∼1 kOe. At higher H, HK rotates up to some angle relative to H and then stays fixed as the sample continues to turn, thus exhibiting a frictional rotation relative to the sample. Nevertheless, HK remains sizeable in magnitude (∼12 kOe). Comparisons are made with analogous results for isostructural (Tb, Y) Ag, where spin-glass order coexists with antiferromagnetism, as well as for various prototypal spin-glass alloys.