| Results of magnetic measurements are presented on the new metallic glass systems (R(,80)G(,20))(,100-x)Fe(,x) and (R(,80)Ga(,20))(,90)B(,10), where R is a rare-earth (i.e., La, Pr, Nd, Sm, Gd, Tb and Er) and G is Ga or Au for 0 (LESSTHEQ) x (LESSTHEQ) 30. High-field magnetization (to 80 kOe) and A.C. and D.C. susceptibility measurements were made from 1.4 K to 300 K. High-field magnetization data are analyzed by an Arrott plot technique and some Gd-based glasses show results consistent with the presence of the recently predicted infinite susceptibility phase of Aharony and Pytte. The magnetic hardness properties of most of these glasses (not containing S-state ions) are discussed in terms of the 'microdomain' model of Callen et al. In many glasses the magnetization reversal seems consistent with a coherent rotation mechanism as is suggested from the thermal variation of the coercivity. The glasses (R(,80)Ga(,20))(,70)Fe(,30) where R is Er and Tb are more complex and show behavior consistent with the presence of domain walls. Magnetic saturation was not obtained (at 80 kOe) on any glass containing an anisotropic rare-earth while glasses based on S-state rare-earths were fairly easily saturated.; Giant intrinsic magnetic hardness is observed in the glasses (R(,80)G(,20))(,100-x)Fe(,x) where R is Nd or Pr and G is Ga or Au for 15 (LESSTHEQ) x (LESSTHEQ) 30. An unusual thermal variation of the coercive field is observed showing peaks at intermediate temperatures ((DBLTURN) 90 K). A phase separation into different amorphous stoichiometries is shown to exist by Fe('57) Mossbauer effect and other measurements. These results are consistent with a recent theory by Paul predicting that magnetic hardness can result from the presence of site-to-site variations in magnetic properties.; Electrical resistivity measurements were made on the above glasses as well as the series (Pr(,80)Ga(,20))(,80)T(,20), where T = Cr, Mn, Co, Ni, Cu and Ga. These show negative temperature coefficients of resistivity at higher temperatures in most cases as well as structure in the resistivity below magnetic ordering temperatures. These results are shown to be consistent with some recent theories (for instance the extended Ziman theory) predicting negative slopes of the resistivity as well as to some theories predicting a magnetic contribution to the resistivity from coherent exchange scattering. |
