Asymmetric magnetoimpedance in exchange-biased systems.

Magnetic systems with competing anisotropies generally exhibit asymmetry between the maximum amplitudes of the right and left maxima in a magnetoimpedance curve. Small errors in positioning the samples at the experimental setup may also produce such asymmetry. In this work, we present a study on the sources of the asymmetry between magnetoimpedance peaks in systems that present the exchange bias phenomenon, by comparing a phenomenological model to experimental data. A set of samples with different repetitions of the NiFe/FeMn exchange-biased bilayer was used in this study. From the frequency evolution of the asymmetry, together with magnetization curves, we were able to identify the sources for the observed magnetoimpedance asymmetry found on our experimental data.

Magnetic interactions in exchange-coupled yet unbiased IrMn/NiCu bilayers.

This paper reports experimental and model magnetization results obtained on exchange-coupled ferromagnet/antiferromagnet (FM/AF) bilayers that show zero net bias. The coercivity of the films, either irradiated with He or implanted with Ge ions at 40 keV, varies significantly with the fluence used. We employed the remanence plots technique in order to estimate the nature of the interactions present and check if there exists a correlation between their type and the coercivity variations. The analysis of the remanence plots through numerical simulations based on the Landau-Lifshitz-Gilbert equation demonstrated that outcomes of interactions within the FM layer could be distinguished from those coming from coupling at the FM/AF interface and that demagnetizing interaction effects could be achieved without the presence of dipolar interactions. Our findings indicate that such experiments could give selective information on modifications caused by a post-deposition treatment in each layer of the film.

A polycrystalline model for magnetic exchange bias.

This work introduces a realistic model for the magnetic behavior of polycrystalline ferromagnet/antiferromagnet (FM/AF) systems with granular interfaces. It considers that, for strong enough interface exchange coupling, the AF layer breaks the adjacent FM into small-sized domains and that at the interface there exist grains with uncompensated spins interacting with the FM magnetizations; the classification of these grains as unstable (rotatable, responsible for a coercivity enhancement) or stable (adding to the bias) depends on both the anisotropy and the magnetic coupling with the adjacent FM. The distinctive characteristic of the model is that the effective rotatable anisotropy changes when the external magnetic field is varied resulting in a non-zero hard-axis coercivity, a feature commonly observed, though little understood and often ignored. The applicability of this model was checked on a typical magnetron-sputtered IrMn/Co bilayer and excellent agreement between experiment and simulation was achieved.

Athermal training due to exchange and dipolar coupling within a granular model for exchange bias.

Athermal training effects in static magnetization curves of exchange-coupled systems have been obtained within a model for polycrystalline antiferromagnetic/ferromagnetic bilayers with a granular interface. Together with parallel coupling between each ferromagnetic grain and stable interface grains that sit underneath it, magnetic exchange and/or dipolar interactions between neighboring stable and partially stable interface grains have been considered. Using realistic anisotropy and coupling parameters in the simulations, training effects have been obtained regardless of the anisotropy type (uniaxial or biaxial) of the interface grains with uncompensated spins. The partial recovery of training effects after application of strong magnetic fields or a change of the sign of the exchange-bias field after training experimentally observed by some authors has been naturally achieved in the framework of the present model.

'But basically you're feeling well, are you?': tag questions in medical consultations.

Tag questions have traditionally been discussed as linguistic strategies used by nonassertive speakers. This article reports the findings of a qualitative study investigating the use of modal and affective tag questions by 3 Australian female general practitioners. Analysis of 29 audiotaped consultations revealed that tag questions were used as both control and involvement strategies. They were found to be employed by doctors for their potential to elicit information from patients, to summarize and confirm information, and to express empathy and provide positive feedback. The implications of these findings are discussed in the light of general patterns of doctor-patient communication as well as more efficient clinical interaction.