57Fe and 151Eu Mössbauer studies of 3d-4f spin interplay in EuFe2-xNixAs2.

The EuFe2-xNixAs2 (with 0 ≤ x ≤ 0.4) compounds exhibiting 3d and/or 4f magnetic order were investigated by means of 57Fe and 151Eu Mössbauer spectroscopy. Additionally, results for EuNi2As2 are reported for comparison. It was found that spin-density-wave order of the Fe itinerant moments is monotonically suppressed by Ni-substitution. However, the 3d magnetic order survives at the lowest temperature up to at least x = 0.12 and it is certainly completely suppressed for x = 0.20. The Eu localized moments order regardless of the Ni concentration, but undergo a spin reorientation with increasing x from alignment parallel to the a-axis in the parent compound, toward c-axis alignment for x > 0.07. Change of the 4f spins ordering from antiferromagnetic to ferromagnetic takes place simultaneously with a disappearance of the 3d spins order what is the evidence of a strong coupling between magnetism of Eu2+ ions and the conduction electrons of [Fe2-xNixAs2]2- layers. The Fe nuclei experience the transferred hyperfine magnetic field due to the Eu2+ ordering for Ni-substituted samples with x > 0.04, while the transferred field is undetectable in EuFe2As2 and for compound with a low Ni-substitution level. It seems that the 4f ferromagnetic component arising from a tilt of the Eu2+ moments to the crystallographic c-axis leads to the transferred magnetic field at the Fe atoms. Superconductivity is not observed down to 1.8 K, although a comparison with 57Fe and 151Eu Mössbauer data for EuFe2As2-based superconductors indicates a similar magnetic structure.

55Mn NMR observation of colossal magnetoresistance effect in Sm0.55Sr0.45MnO3.

Temperature dependent 55Mn NMR study of Sm0.55Sr0.45MnO3 is reported. Previous bulk magnetization measurements have shown that below T C ~ 125 K the sample is ferromagnetic metallic (FMM) and above TC it is charge ordered and insulating. In present report, we show that from zero-field NMR a single line double-exchange (DE) signal is observed at temperatures up to 139 K, which is due to a presence of FMM clusters also above T C. The intensity of the DE line follows the temperature dependence of the magnetization measured at 0.01 T. When a magnetic field up to 2 T is applied at 139 K (i.e. 14 K above T C), a strong increase in NMR intensity of the DE line is observed indicating that content of FMM regions increases. This reveals that metallicity is induced in the material by the applied magnetic field and explains the observed colossal magnetoresistance (CMR) effect at the microscopic level. The observation agrees with previous results, which confirm that the percolation of the FMM clusters is responsible for the CMR effect. The shift of the resonant frequency in the applied field is three times smaller compared to decrease expected from gyromagnetic ratio, which indicates an antiferromagnetic coupling between the FMM clusters.

63Cu nuclear magnetic resonance study of Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4): Ni-induced spin density oscillation and modification of the low energy spin fluctuations.

We report the results from a (63)Cu nuclear magnetic resonance (NMR) study of the electron-doped high temperature superconducting cuprate (HTSC) Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4). We find that Ni induces a magnetic broadening of the (63)Cu NMR spectra that can be interpreted in terms of an induced spin density oscillation about the Ni site, similar to that reported from (63)Cu NMR measurements on the hole-doped HTSCs when Zn is partially substituted for Cu. There is also an additional temperature-dependent contribution to the (63)Cu spin-lattice relaxation rate that can be interpreted in terms of an Ni-induced modification of the low energy spin fluctuations. Furthermore, the spin fluctuations are intrinsically spatially inhomogeneous and additional inhomogeneities are induced by Ni.

An empirical assessment of bulimic patients using multiple measures.

This paper examines personality and clinical assessment data from bulimic patients and from a control group of normal volunteer subjects. Thirty-eight bulimic females representing consecutive admissions to an outpatient treatment program were administered a battery of tests including the MMPI, FIRO-B, Beck Depression Inventory, Moos Family Environment Scale, Bem Sex Role Inventory, and Conte Borderline Syndrome Index. Twenty-six normal females also completed this testing battery. As expected, bulimics differed from normals on several clinical scales, including the MMPI, Beck Depression Inventory, and Conte Borderline Syndrome Index. More importantly, however, were the results of the cluster analysis of the bulimic MMPI scores which demonstrated two clearly defined subtypes of bulimia: a mildly disturbed group that shows developmental conflicts and adjustment difficulties, and a severely disturbed group that displays low ego strength and characteristics suggesting an Axis II personality disturbance. The other testing measures failed to reach significance levels. Implications for assessment and treatment are explored in the context of these results.