The dynamic and static stress changes during the 2000 Tottori earthquake have been recovered from the results of waveform inversion. We use the DEM to solve the elastodynamic equation specifying the slip along the fault obtained by a kinematic fault model. The resulting shear stress distribution suggests an explanation of the foreshock and aftershock distributions. We conclude that the fault zone heterogeneity is strong and most of the foreshocks and aftershocks were located in the zone of negative stress drop and mainly in the area surrounding the asperity. This suggests that the asperity behaved as a barrier during the foreshocks and after the main shock the stress in the area surrounding the asperity increased and triggered most of the aftershocks. The foreshock distribution was confined to a finite localized zone in the central part of the fault, suggesting that this zone was bordered by barriers.

No abstract

The susceptibility and thermal expansion of Yb 1−x R x InCu 4 (x 0.25; R = Y, La and Ce) have been measured at ambient and high pressures. These compounds undergo a first-order valence transition from an intermediatevalence state to a nearly trivalent state with increasing temperature. The valence change at the transition is δv ∼ 0.1 for YbInCu 4. It decreases on both alloying and applying pressure for all the compositions studied. From the pressure effect on the susceptibility of YbInCu 4 , the Grüneisen parameter for the Kondo energy K is determined to be −34.5 and −20 for the low-temperature and the high-temperature state, respectively. The coefficient characterizing the hybridization strength between the 4f and conduction electrons for the intermediate-valence state is nearly five times larger than that for the hightemperature local-moment state. The obtained results suggest that the change of the 4f-conduction band electron hybridization rather than the volume dependence of the Kondo interaction is responsible for a large modification of the physical properties of the YbInCu 4-based compounds at the valence transition.

Crystallographic and magnetic properties of Co 2 Mn 1−x Fe x Sn and Co 2 Mn 1−y Cr y Sn Heusler alloys were studied using x-ray diffraction, scanning electron microscopy with energy dispersive x-ray analysis, magnetization measurements and Mössbauer spectroscopy. We found that the intermetallic compounds crystallize into a single phase with the L2 1 -type Heusler structure at the concentration of 0 x 0.5 for Co 2 Mn 1−x Fe x Sn and 0 y 0.3 for Co 2 Mn 1−y Cr y Sn. The spontaneous magnetization increases when Mn is substituted with Fe and decreases when Mn is substituted with Cr. The values of hyperfine field at the Sn nuclear sites in Co 2 Mn 1−x Fe x Sn and Co 2 Mn 1−y Cr y Sn also increase or decrease in combination with the size of magnetization. These measurements suggest that the Slater-Pauling behaviour in half-metallic full-Heusler alloys provides a good description of the substitution effect of Mn with Fe or Cr.

The susceptibility and high-field magnetization of single-crystalline Yb 1−x Y x InCu 4 (x = 0, 0.2 and 0.3) samples have been measured for different field orientations at ambient and high pressures. The compounds with x = 0 and 0.2 undergo a first-order valence transition from the intermediate-valence state to the trivalent state on increasing either temperature or magnetic field. The magnetization and susceptibility of these compounds have appreciable anisotropy in both states. The magnetic phase diagram of Yb 1−x Y x InCu 4 determined at ambient pressure is also anisotropic, which is explained by the crystal-field calculations for the free Yb ion in the high-temperature phase. Moreover, the low-temperature magnetization process for x = 0.2 and 0.3 has been measured in low fields under high pressure; it shows anisotropic ferromagnetic ordering.

No abstract

No abstract