Spontaneous exchange bias formation driven by a structural phase transition in the antiferromagnetic material.

Most of the magnetic devices in advanced electronics rely on the exchange bias effect, a magnetic interaction that couples a ferromagnetic and an antiferromagnetic material, resulting in a unidirectional displacement of the ferromagnetic hysteresis loop by an amount called the 'exchange bias field'. Setting and optimizing exchange bias involves cooling through the Néel temperature of the antiferromagnetic material in the presence of a magnetic field. Here we demonstrate an alternative process for the generation of exchange bias. In IrMn/FeCo bilayers, a structural phase transition in the IrMn layer develops at room temperature, exchange biasing the FeCo layer as it propagates. Once the process is completed, the IrMn layer contains very large single-crystal grains, with a large density of structural defects within each grain, which are promoted by the FeCo layer. The magnetic characterization indicates that these structural defects in the antiferromagnetic layer are behind the resulting large value of the exchange bias field and its good thermal stability. This mechanism for establishing the exchange bias in such a system can contribute towards the clarification of fundamental aspects of this exchange interaction.

[Ethical issues in primary care during the coronavirus (SARS-CoV-2) pandemic]. / Problemas éticos en atención primaria durante la pandemia del coronavirus (SARS-CoV-2).

Public health emergencies, such as the current SARS-CoV-2 coronavirus pandemic, have led to tragic resource constraints that prevent lives from being saved. This has led to tensions in patient-centered care as the backbone of the system in normal conditions and the same care in emergencies originating in the COVID-19. In this review we address some of the healthcare, organizational and ethical problems that this scenario has caused in primary care such as: cancellation of programmed activities; scarce home care and follow-up of elderly, chronically ill and immobilized patients; shortage of PPE and the exposure to risk of healthcare professionals, and finally the problems associated with telemedicine and telephone attention to patients.

Combined alternating gradient force magnetometer and susceptometer system.

We report the design, fabrication, and characterization of a new system that combines the performances of two different types of magnetic characterization systems, Alternating Gradient Force Magnetometers (AGFM) and susceptometers. The flexibility of our system is demonstrated by its capability to be used as any of them, AGFM or susceptometer, without any modification in the experimental set-up because of the electronics we have developed. Our system has a limit of sensitivity lower than 5 × 10(-7) emu. Moreover, its main advantage is demonstrated by the possibility of measuring small quantities of materials under DC or AC magnetic fields that cannot properly be measured with a commercial vibrating sample magnetometers or AGFM.