SPIN FLUCTUATIONS IN AN AMORPHOUS ALLOY

Enhancement of the effective electron mass by spin fluctuations (SF's) has been studied in a-FexZr100-x (27%less than or equal to x less tha n or equal to 39%) by low-temperature calorimetry. Previous magnetizat ion measurements on paramagnetic a-FexZr100-x are also presented and a nalyzed to extract the ground-state susceptibility chi(T=0) The low sp in fluctuation temperature of similar to 7 K and the stable amorphous structure make it possible to unambiguously distinguish between magnet ic and nonmagnetic contributions to the electronic specific heat. The SF contribution to the specific heat shows a clear maximum around the critical composition for the onset of magnetic order (x(c) similar to 37%), with the mass enhancement parameter lambda(SF) reaching similar to 1. Complete quenching of SF's by both temperature and an external m agnetic field have been observed. As a result of its low characteristi c temperature (T(SF)similar to 7 K), a-Fe36Zr64 shows the dearest evid ence to date of the effects of SF's on electronic properties.