Quasi-One-Dimensional Spin Dynamics in dd-Electron Heavy-Fermion Metal Y1−x_{1-x}Scx_xMn2_2

Slow spin fluctuations ($\nu < 10^{12}$ s$^-1$) observed by the muon spin relaxation technique in Y$_{1-x}$Sc$_x$Mn$_2$ exhibits a power law dependence on temperature ($\nu \propto T^\alpha$), where the power converges asymptotically to unity ($\alpha\rightarrow 1$) as the system moves away from spin-glass instability with increasing Sc content $x$. This linear $T$ dependence, which is common to that observed in LiV$_2$O$_4$, is in line with the prediction of the "intersecting Hubbard chains" model for a metallic pyrochlore lattice, suggesting that the geometrical constraints to t2g bands specific to the pyrochlore structure serve as a basis of the $d$-electron heavy-fermion state.Comment: 5 pages, 4 figures, to appear in J. Phys. Soc. Jp

First order phase transition from ferromagnetism to antiferromagnetism in Ce(Fe0.96_{0.96}Al0.04_{0.04})2_2

Taking the pseudobinary C15 Laves phase compound Ce(Fe$_{0.96}$Al$_{0.04}$)$_2$ as a paradigm for studying a ferromagnetic to antiferromagnetic phase transition, we present interesting thermomagnetic history effects in magnetotransport as well as magnetisation measurements across this phase transition. A comparison is made with history effects observed across the ferromagnetic to antiferromagnetic transition in R$_{0.5}$Sr$_{0.5}$MnO$_3$ crystals.Comment: 11 pages of text and 4 figures; submitted to Physical Review Letter

Magnetic fluctuations in frustrated Laves hydrides R(Mn_{1-x}Al_{x})_{2}H_{y}

By neutron scattering, we have studied the spin correlations and spin fluctuations in frustrated Laves hydrides, where magnetic disorder sets in the topologically frustrated Mn lattice. Below the transition towards short range magnetic order, static spin clusters coexist with fluctuating and alsmost uncorrelated spins. The magnetic response shows a complexe lineshape, connected with the presence of the magnetic inhomogeneities. Its analysis shows the existence of two different processes, relaxation and local excitations, for the spin fluctuations below the transition. The paramagnetic fluctuations are discussed in comparison with classical spin glasses, cluster glasses, and non Fermi liquid itinerant magnets

Calculation of magnetic anisotropy energy in SmCo5

SmCo5 is an important hard magnetic material, due to its large magnetic anisotropy energy (MAE). We have studied the magnetic properties of SmCo5 using density functional theory (DFT) calculations where the Sm f-bands, which are difficult to include in DFT calculations, have been treated within the LDA+U formalism. The large MAE comes mostly from the Sm f-shell anisotropy, stemming from an interplay between the crystal field and the spin-orbit coupling. We found that both are of similar strengths, unlike some other Sm compounds, leading to a partial quenching of the orbital moment (f-states cannot be described as either pure lattice harmonics or pure complex harmonics), an optimal situation for enhanced MAE. A smaller portion of the MAE can be associated with the Co-d band anisotropy, related to the peak in the density of states at the Fermi energy. Our result for the MAE of SmCo5, 21.6 meV/f.u., agrees reasonably with the experimental value of 13-16 meV/f.u., and the calculated magnetic moment (including the orbital component) of 9.4 mu_B agrees with the experimental value of 8.9 mu_B.Comment: Submitted to Phys. Rev.

Social differentiation and embodied dispositions: a qualitative study of maternal care-seeking behaviour for near-miss morbidity in Bolivia

<p>Abstract</p> <p>Background</p> <p>Use of maternal health care in low-income countries has been associated with several socioeconomic and demographic factors, although contextual analyses of the latter have been few. A previous study showed that 75% of women with severe obstetric morbidity (near-miss) identified at hospitals in La Paz, Bolivia were in critical conditions upon arrival, underscoring the significance of pre-hospital barriers also in this setting with free and accessible maternal health care. The present study explores how health care-seeking behaviour for near-miss morbidity is conditioned in La Paz, Bolivia.</p> <p>Methods</p> <p>Thematic interviews with 30 women with a near-miss event upon arrival at hospital. Near-miss was defined based on clinical and management criteria. Modified analytic induction was applied in the analysis that was further influenced by theoretical views that care-seeking behaviour is formed by predisposing characteristics, enabling factors, and perceived need, as well as by socially shaped habitual behaviours.</p> <p>Results</p> <p>The self-perception of being fundamentally separated from "others", meaning those who utilise health care, was typical for women who customarily delivered at home and who delayed seeking medical assistance for obstetric emergencies. Other explanations given by these women were distrust of authority, mistreatment by staff, such as not being kept informed about their condition or the course of their treatment, all of which reinforced their dissociation from the health-care system.</p> <p>Conclusion</p> <p>The findings illustrate health care-seeking behaviour as a practise that is substantially conditioned by social differentiation. Social marginalization and the role health institutions play in shaping care-seeking behaviour have been de-emphasised by focusing solely on endogenous cultural factors in Bolivia.</p