We present experimental data on the magnetization M(H) of a CuMn 1 at. % in the range Tc≤ T ≤ 4 Tc, 0 < H < 7 teslas. We took special precautions in order to eliminate systematic errors and improve the reliability of the data. It was then possible to study the temperature dependence of the first coefficients A 1, A3, A5 in the expansion of the low field magnetization data in terms of odd powers of [FORMULA], in the range 1.1 Tc ≤ T ≤ 4 Tc. From the divergence of A3 and A5 (which vary over 3 and 6 orders of magnitude respectively in this range), we derive two exponents (γ = 3.25, β = 0.75 ± 0.25) which allow the rescaling of all our data points onto a universal function. The success of the scaling argument is strong evidence in favour of the existence of a phase transition in three dimensions for RKKY spin glasses

An anomalous Hall effect is measured in pure decagonal A18OMn20 and A178Mn». We show that the Hall resistivity pH is linear with the magnetization M measured for the same fields and temperatures: pH(H T) =ROH +4wRsM (H T). The very dominant term RsM of p& reveals a strong spin-orbit scattering, which is observed in Al-Mn quasicrystals. Rs is found to be temperature independent in the range 6.5 -110 K. From our susceptibility, specific-heat, and magnetoresistance data, we deduce that M results from a very low fraction of magnetic moments, which increase drastically with the nominal Mn concentration and that are correlated by Ruderman-Kittel-Kasuya-Yosida interactions. In this respect, the Al-Mn decagonal phase behaves very similarly to previously measured Al-Mn icosahedral and amorphous phases.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

No abstract