Exploring the origins of perpendicular magnetic anisotropy in amorphous Tb-Co via changes in medium-range ordering

Amorphous thin films of Tb$_{17}$Co$_{83}$ (a-Tb-Co) grown by magnetron co-sputtering exhibit changes in magnetic anisotropy with varying growth and annealing temperatures. The magnetic anisotropy constant increases with increasing growth temperature, which is reduced or vanishes upon annealing at temperatures above the growth temperature. The proposed explanation for this growth-induced anisotropy in high orbital moment Tb-based transition metal alloys such as a-Tb-Co is an amorphous phase texturing with preferential in-plane and out-of-plane local bonding configurations for the rare-earth and transition metal atoms. Scanning nanodiffraction performed in a transmission electron microscope (TEM) is applied to a-Tb$_{17}$Co$_{83}$ films deposited over a range of temperatures to measure relative changes in medium-range ordering (MRO). These measurements reveal an increase in MRO with higher growth temperatures and a decrease in MRO with higher annealing temperatures. The trend in MRO indicates a relationship between the magnetic anisotropy and local atomic ordering. Tilting select films between 0$^{\circ}$ and 40$^{\circ}$ in the TEM measures variations in the local atomic structure a function of orientation within the films. The findings support claims that preferential ordering along the growth direction results from temperature-mediated adatom configurations during deposition, and that oriented MRO correlates with the larger anisotropy constants.Comment: 13 pages, 9 figure

Public health restrictions, directives, and measures in Arctic countries in the first year of the COVID-19 pandemic

Beginning January of 2020, COVID-19 cases detected in Arctic countries triggered government policy responses to stop transmission and limit caseloads beneath levels that would overwhelm existing healthcare systems. This review details the various restrictions, health mandates, and transmission mitigation strategies imposed by governments in eight Arctic countries (the United States, Canada, Greenland, Norway, Finland, Sweden, Iceland, and Russia) during the first year of the COVID-19 pandemic, through 31 January 2021s31 January 2021. We highlight formal protocols and informal initiatives adopted by local communities in each country, beyond what was mandated by regional or national governments. This review documents travel restrictions, communications, testing strategies, and use of health technology to track and monitor COVID-19 cases. We provide geographical and sociocultural background and draw on local media and communications to contextualise the impact of COVID-19 emergence and prevention measures in Indigenous communities in the Arctic. Countries saw varied case rates associated with local protocols, governance, and population. Still, almost all regions maintained low COVID-19 case rates until November of 2020. This review was produced as part of an international collaboration to identify community-driven, evidence-based promising practices and recommendations to inform pan-Arctic collaboration and decision making in public health during global emergencies