Abstract
We report ESR measurements on two concentrated metallic spin glasses; a-Fe 7Ni 13P 14B 6 and a-Mn 48B 52 encompassing wide ranges of frequency (2–35 GHz) and temperature (4–300 K). The temperature dependence of the linewidth ( T) falls into three regimes; (i) T ≈ T 0, independent of T for T around 2–3 T SG, (ii) ( T- T 0)= - a + bT for T ⪆ 3 T SG; (iii) ( T- T 0) α T exp(- T/ T 0) for T ⪅2 T SG. The resonance fields yield a magnetisation varying as M( T, H)=[ M ∈( T) - C'/√ H] with M ∈( T) reducing linearly with T 3/2 for T ⪆ 20 K. At low T an anisotropy field becomes evident and varies with T as (1 - T/2 T SG). Comparison with a recent model based on coupling to two level systems is formally suggestive but quantitatively unsatisfactory.
Published Version
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