Features of structure, magnetic state and electrodynamic performance of SrFe12-xInxO19.

Indium-substituted strontium hexaferrites were prepared by the conventional solid-phase reaction method. Neutron diffraction patterns were obtained at room temperature and analyzed using the Rietveld methods. A linear dependence of the unit cell parameters is found. In3+ cations are located mainly in octahedral positions of 4fVI and 12 k. The average crystallite size varies within 0.84-0.65 µm. With increasing substitution, the TC Curie temperature decreases monotonically down to ~ 520 K. ZFC and FC measurements showed a frustrated state. Upon substitution, the average and maximum sizes of ferrimagnetic clusters change in the opposite direction. The Mr remanent magnetization decreases down to ~ 20.2 emu/g at room temperature. The Ms spontaneous magnetization and the keff effective magnetocrystalline anisotropy constant are determined. With increasing substitution, the maximum of the ε/ real part of permittivity decreases in magnitude from ~ 3.3 to ~ 1.9 and shifts towards low frequencies from ~ 45.5 GHz to ~ 37.4 GHz. The maximum of the tg(α) dielectric loss tangent decreases from ~ 1.0 to ~ 0.7 and shifts towards low frequencies from ~ 40.6 GHz to ~ 37.3 GHz. The low-frequency maximum of the µ/ real part of permeability decreases from ~ 1.8 to ~ 0.9 and slightly shifts towards high frequencies up to ~ 34.7 GHz. The maximum of the tg(δ) magnetic loss tangent decreases from ~ 0.7 to ~ 0.5 and shifts slightly towards low frequencies from ~ 40.5 GHz to ~ 37.7 GHz. The discussion of microwave properties is based on the saturation magnetization, natural ferromagnetic resonance and dielectric polarization types.

Anisotropic sensor and memory device with a ferromagnetic tunnel barrier as the only magnetic element.

Multiple spin functionalities are probed on Pt/La2Co0.8Mn1.2O6/Nb:SrTiO3, a device composed by a ferromagnetic insulating barrier sandwiched between non-magnetic electrodes. Uniquely, La2Co0.8Mn1.2O6 thin films present strong perpendicular magnetic anisotropy of magnetocrystalline origin, property of major interest for spintronics. The junction has an estimated spin-filtering efficiency of 99.7% and tunneling anisotropic magnetoresistance (TAMR) values up to 30% at low temperatures. This remarkable angular dependence of the magnetoresistance is associated with the magnetic anisotropy whose origin lies in the large spin-orbit interaction of Co2+ which is additionally tuned by the strain of the crystal lattice. Furthermore, we found that the junction can operate as an electrically readable magnetic memory device. The findings of this work demonstrate that a single ferromagnetic insulating barrier with strong magnetocrystalline anisotropy is sufficient for realizing sensor and memory functionalities in a tunneling device based on TAMR.

Isothermal anisotropic magnetoresistance in antiferromagnetic metallic IrMn.

Antiferromagnetic spintronics is an emerging field; antiferromagnets can improve the functionalities of ferromagnets with higher response times, and having the information shielded against external magnetic field. Moreover, a large list of aniferromagnetic semiconductors and metals with Néel temperatures above room temperature exists. In the present manuscript, we persevere in the quest for the limits of how large can anisotropic magnetoresistance be in antiferromagnetic materials with very large spin-orbit coupling. We selected IrMn as a prime example of first-class moment (Mn) and spin-orbit (Ir) combination. Isothermal magnetotransport measurements in an antiferromagnetic-metal(IrMn)/ferromagnetic-insulator thin film bilayer have been performed. The metal/insulator structure with magnetic coupling between both layers allows the measurement of the modulation of the transport properties exclusively in the antiferromagnetic layer. Anisotropic magnetoresistance as large as 0.15% has been found, which is much larger than that for a bare IrMn layer. Interestingly, it has been observed that anisotropic magnetoresistance is strongly influenced by the field cooling conditions, signaling the dependence of the found response on the formation of domains at the magnetic ordering temperature.

Calibration of ac and dc magnetometers with a Dy2O3 standard.

The ac susceptibility and magnetization curves of a glued Dy(2)O(3) powder sample are measured by an ac susceptometer and a dc superconducting quantum interference device magnetometer, both of which have been calibrated previously. It is shown that the magnetic moment of the paramagnetic sample as a function of field and temperature may be accurately expressed by a combination of the Curie-Weiss law and the Langevin function at T > 45 K with three adjusting parameters, so that the dc magnetization curves and the magnitude and phase of ac susceptibility at different values of dc bias field measured by any magnetometer can be calibrated by using Dy(2)O(3) as a standard. The expressions are empirical and cannot be justified in the entire field and temperature range by existing theories of paramagnetism. Below 10 K, indication of approaching a possible phase transition is found. It is shown that pure Dy(2)O(3) powder may be used as a primary standard, with susceptibility [13.28(T + 17)](-1) emu/Oe/g at T > 50 K and H < 10 kOe, in consistency with the Curie-Weiss law and the quantum mechanical theory of paramagnetism.

Fístula recto-vaginal / Rectal-vaginal fistula

Se analiza la experiencia acumulada de 10 años en el tratamiento de fístulas recto vaginales de diversa etiología. Un total de 10 casos fueron tratados durante este período en el Hospital Regional de Rancagua. Las causas de origen traumático gineco-obstétrico son las más frecuentes (70 por ciento). Todas las fístulas fueron tratadas después de tres meses de aparecidas, utilizando diversas técnicas quirúrgicas. Efectuándose principalmente la reparación local por vía endorrectal, en algunos casos con colostomía previa de derivación. No hubo complicaciones ni mortalidad en nuestra serie

Divertículo de Meckel y hemorragia digestiva en el adulto / Meckel's diverticulum and digestive tract hemorrhage in the adult

Se presentan dos casos de hemorragia digestiva en el adulto originada en el divertículo de Meckel. En ambos casos se efectuó intervención quirúrgica, consistente en la resección intestinal de la zona diverticular, con buen resultado. Se comenta la escasa frecuencia de la complicación hemorrágica, en esta anomalía anatómica especialmente en el adulto. Los autores se manifiestan partidarios de la remoción del divertículo, en caso de hallazgo incidental, dada la gravedad de su complicación