de Haas-van Alphen measurements in Ce x La 12x B 6 intermetallics reveal the existence of long-lived quasiparticles for all 0 , x , 1. This is accompanied by the enhancement of the field-dependent effective mass, together with changes to the topology of the Fermi surface developing very early in the series, and with the effective mass eventually exhibiting a maximum near x ϳ 0.9. One of the spin contributions to the signal is also observed to disappear at very low x, indicating a spin polaritydependent scattering mechanism. [S0031-9007(99)09074-2]

We have determined the Fermi surface and effective masses of electronic carriers in ferromagnetic EuB 6 from pulsed field magnetization and steady field torque Landau quantum oscillatory measurements. To aid in the interpretation of the measurements, superconducting quantum interference device magnetometer measurements of the overall magnetization were made on the same samples. The results are consistent with recent electronic structure calculations and show both an electron and a hole pocket located at the X point in the Brillouin zone. ͓S0163-1829͑98͒03945-9͔

Resonant ultrasound spectroscopy (RUS) and pulse-echo (PE) superposition techniques have been used to determine the three independent elastic-stiffness constants C 11 , C 12 , and C 44 as a function of temperature for single crystals of 70Fe-15Ni-15Cr alloy. The values of the elastic moduli determined using RUS and PE are in very good agreement within the range of uncertainties. This particular ternary composition of Fe, Ni, and Cr undergoes an fcc-bcc structural phase transformation near 190 K resulting in a low-temperature ferromagnetic phase. The Debye characteristic temperature was determined to be 447 K from PE and 451 K from RUS measurements. The Zener elastic anisotropy A ϭ 2C 44 /(C 11 Ϫ C 12 ) is nearly constant: A ϭ 3.53 Ϯ 0.16 in Fe-Ni-Cr alloys with similar compositions. For these alloys, only small variations are observed in the Grüneisen parameter, ␥ Ϸ 2.08, and in the Poisson ratio, v [hkl] ϭ 0.293 Ϯ 0.013.

We report quantitative experimental results regarding concentration fluctuations based on a small-angle light-scattering setup. A shadowgraph technique was used to record concentration fluctuations in a free-diffusion cell filled with colloids. Our experimental setup includes an objective attached to the CCD camera to increase the field of view. We performed two separate experiments, one with 20 nm gold and the other with 200 nm silica colloids, and extracted both the structure factors and the correlation time during the early stages of concentration fluctuations. The temporal evolution of fluctuations was also qualitatively investigated using recursive plots and spatial-temporal sections of fluctuating images. We found that the correlation time versus wavenumber for gold nanocolloids is concave shaped, whereas, for silica colloids, it is convex shaped. The difference in correlation time behavior is not only due to the size of the particle, but also to possible plasmonic interactions in gold colloids.