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Differential scanning calorimetry technique was used to investigate phase equilibria in the YbCl2–MCl (M = Li, Na) binary systems. The YbCl2–LiCl system exhibits an eutectic located at YbCl2 mole fraction x = 0.415 (733 K) and a LiYb2Cl5 stoichiometric compound that is formed at 711 K and melts incongruently at 742 K. The YbCl2–NaCl system exhibits an eutectic located at YbCl2 mole fraction x = 0.559 (764 K). In both systems the formation of solid solutions in the MCl-rich side (M = Li, Na) has been found. The molar enthalpies of mixing (ΔHMIX) in the liquid YbCl2–MCl (M = Na, K) mixtures have been measured at 1085 K with a Calvet-type high temperature microcalorimeter in the entire range of composition. A negative value of mixing enthalpy was observed for all melts. The minimum value was of approximately: − 2.5, and − 7.5 kJ mol−1, for systems with NaCl and KCl, respectively. All the experimental results along with the available literature data were used to optimize the thermodynamic properties of the investigated systems using the CALPHAD method. [ABSTRACT FROM AUTHOR]

BACKGROUND: The identification of temporal thresholds or shifts in animal movement informs ecologists of changes in an animal's behaviour, which contributes to an understanding of species' responses in different environments. In African savannas, rainfall, temperature and primary productivity influence the movements of large herbivores and drive changes at different scales. Here, we developed a novel approach to define seasonal shifts in movement behaviour by examining the movements of a highly mobile herbivore (elephant; Loxodonta africana), in relation to local and regional rainfall patterns. METHODOLOGY/PRINCIPAL FINDINGS: We used speed to determine movement changes of between 8 and 14 GPS-collared elephant cows, grouped into five spatial clusters, in Kruger National Park, South Africa. To detect broad-scale patterns of movement, we ran a three-year daily time-series model for each individual (2007-2009). Piecewise regression models provided the best fit for elephant movement, which exhibited a segmented, waveform pattern over time. Major breakpoints in speed occurred at the end of the dry and wet seasons of each year. During the dry season, female elephant are constrained by limited forage and thus the distances they cover are shorter and less variable. Despite the inter-annual variability of rainfall, speed breakpoints were strongly correlated with both local and regional rainfall breakpoints across all three years. Thus, at a multi-year scale, rainfall patterns significantly affect the movements of elephant. The variability of both speed and rainfall breakpoints across different years highlights the need for an objective definition of seasonal boundaries. CONCLUSIONS/SIGNIFICANCE: By using objective criteria to determine behavioural shifts, we identified a biologically meaningful indicator of major changes in animal behaviour in different years. We recommend the use of such criteria, from an animal's perspective, for delineating seasons or other extrinsic shifts in ecological studies, rather than arbitrarily fixed definitions based on convention or common practice.

When two ferromagnetic layers have a common resonance frequency, the usual spin-pumping broadening may be reduced by dynamic exchange coupling. Utilizing the antiferromagnetic coupling between Co and Gd, we explore the change in ferromagnetic resonance accompanying a spontaneous transition from parallel to antiparallel magnetic alignment of two Co films below the compensation temperature Tcomp. Above Tcomp, the data are consistent with conventional models. However, a rapid doubling of magnetic damping accompanies the realignment, which is reminiscent of resistivity changes in giant magnetoresistance. [ABSTRACT FROM AUTHOR]

The magnetocaloric effect of a La[sub 2/3](Ca,Pb)[sub 1/3]MnO[sub 3] single crystal was examined. From the measurements of isothermal magnetization and heat capacity around the Curie temperature, we have calculated the maximum isothermal magnetic entropy change as ∼7.5 J/kgK and the adiabatic temperature changes as ∼5.6 K, near room temperature for a 7 T magnetic field variation. Besides, the sharp drop of resistivity at the insulator-metal transition associated with the magnetic transition gives rise to a large temperature coefficient of resistance (TCR). For the La[sub 0.7]Ca[sub 0.3]MnO[sub 3] and La[sub 2/3](Ca,Pb)[sub 1/3]MnO[sub 3] single crystal, the peak of TCR is ∼50%/K at 218 K and ∼10%/K at 290 K, respectively. [ABSTRACT FROM AUTHOR]

We report a detailed study of ac/dc magnetization and longitudinal/transverse transport properties of La[sub 1.2]Sr[sub 1.8]Mn[sub 2]O[sub 7] single crystals below T[sub c] = 118 K. We find that the resistivity minimum at 40 K is related to the reentrant spin glass phase at the same temperature, accompanied by additional anomalous Hall effects. The carrier concentration from the ordinary Hall effects remains constant during the transition and is close to the nominal doping level (0.4 holes/Mn). The spin glass behavior comes from the competition between ferromagnetic double exchange and antiferromagnetic superexchange interactions, which leads to phase separation, i.e., a mixture of ferromagnetic and antiferromagnetic clusters, representing the canted antiferromagnetic state. [ABSTRACT FROM AUTHOR]

Deals with the topics discussed during the 31st Conference on Magnetism and Magnetic Materials, which focused on spin-glass transition in three-dimensions. List of panelists; Speculation on the nature of the phase transition in dilute alloys; Behavior of the coefficients for copper manganite.

Examines the magnetic ordering of highly perfect single-crystal multilayer films of alternate layers of magnetic dysprosium and nonmagnetic yttrium prepared by molecular beam epitaxy. Results of neutron diffraction; Mechanism behind the long-range spin coupling; Information on the magnetic field dependence.

The magnetic properties of a series of ferromagnetic/antiferromagnetic (FM/AFM) superlattices are studied. The multilayers are composed of five La2/3Sr1/3MnO3/Pr2/3Ca1/3MnO3 (LSMO/PCMO) bilayers, grown by pulsed laser deposition using SrTiO3 as the substrate. The evolution of the magnetic moment with the AFM PCMO layer thickness (0<=tA<=7.6 nm) is analyzed and is found to be strongly affected by the strain fields introduced by the FM/AFM interfaces. The effect on the LSMO is the appearance of a magnetic dead layer of ∼1.5 nm, close to the interface with the PCMO. On the contrary, the magnetic moment of PCMO is remarkably enhanced for thicknesses tA around 3.5 nm, where nanometric FM droplets would find the optimal strain conditions to be accommodated within the AFM PCMO spacer. The implications of these findings on the magnetoresistance response are discussed. [ABSTRACT FROM AUTHOR]

The Hall resistivity, magnetoresistance, and magnetization of La[SUB1-x]Ca[SUBx]CoO[SUB3] epitaxial films with 0.25≥x≥0.4 grown on lanthanum aluminate were measured in fields up to 7 T. The x = 1/3 film shows a reentrant metal insulator transition. Below 100 K, the x = 1/3 and 0.4 films have significant coercivity which increases with decreasing temperature. At low temperature the Hall resistivity remains large and essentially field independent in these films, except for a sign change at the coercive field that is more abrupt than the switching of the magnetization. A unique magnetoresistance behavior accompanies this effect. These results are discussed in terms of a percolation picture and the mixed spin state model for this system. We propose that the low-temperature Hall effect is caused by spin-polarized carriers scattering off of orbital disorder in the spin-ordered clusters. [ABSTRACT FROM AUTHOR]

The magnetothermopower and magnetoresistance of two copper/cobalt multilayers grown on grooved indium phosphide were measured between 100 K and 295 K. One sample was deposited at an angle onto a grooved substrate such that transport properties are measured between layers rather than parallel to them (CPP); the other was deposited perpendicular to the substrate, so that the transport properties are measured at an angle to the planes (CAP). The data show the magnetothermopower to vary inversely with the resistivity, as predicted by the Mott formula if the magnetoresistance is determined by the ratio α of majority to minority densities of states at the Fermi energy E[sub F] in the magnetic metal. Using this result, we can collapse the thermopower data at various temperatures to find that α[sup ′]/α is 0.6 eV[sup -1] for the CPP sample and 0.7 eV[sup -1] for the CAP sample, where α[sup ′]≡(∂α/∂E)[sub E[sub F]]. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The heat capacity of single crystal La[sub 0.7]D[sub 0.3]MnO[sub 3], where D=Ca, Sr, has been measured through the Curie point in fields up to 70 kOe. The magnetic contribution of the Ca sample exhibits a sharp heat capacity peak at T[sub C]=218 K in zero field. The peak broadens and decreases in height with increasing field but, unlike an ordinary ferromagnet, the peak shifts substantially in temperature. As a consequence, the heat capacity data cannot be collapsed into a single scaling function. These features indicate that the transition is not an ordinary second-order ferromagnetic transition. Preliminary heat capacity data from the Sr-doped single crystal, with T[sub C]=360 K, do not exhibit the same shift in peak position with applied field. We attribute the difference in behavior between Ca- and Sr-doped samples to a change in the nature of the phase transition as T[sub C] lowers. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents information on a study which measured the Hall resistivity of lanthanum(calcium,lead)manganese oxide single crystals. Hall effect measurements; Residual resistivity and magnetoresistance of the crystal; Conclusions.