Earth’s mantle could be more magnetic than once thought

The Earth’s mantle has long been considered non-magnetic, due to high temperatures at depth.

An international team of scientists used ID18 to study the iron oxide hematite (Fe2O3), a strongly magnetic mineral, at temperatures and pressures found down to the Earth’s lower mantle. Their study, published in Nature, provides evidence that hematite retains magnetic properties at the depth of the transition zone between the upper and lower mantle at certain temperatures and could therefore be a source of magnetic anomalies there.
Scientists have traditionally considered the Earth’s mantle to be non-magnetic due to its elevated temperatures being too high to retain any magnetism in the constituting minerals. However, satellite and aeromagnetic data provide evidence for magnetic anomalies in the mantle, particularly around cooler areas such as subduction zones (tectonic plate boundaries where one plate is forced underneath another). The source of the anomalies remains largely unknown, but iron oxides are considered a likely source due to their high critical temperatures. Of these, hematite (Fe2O3) is the dominant iron oxide at depths of around 300 – 600 km below the Earth’s surface – a transition zone between the upper and the lower mantle.

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The first observation of near-room-temperature superconductivity

For decades, room-temperature superconductivity has been one of physics’ ultimate goals, a Holy Grail-like objective that seems to keep drifting within realization yet always stubbornly out of reach. Various materials, theories, and techniques have been proposed and explored in search of this objective, but its realization has remained elusive. Yet recent experimental work on hydrogen-rich materials at high pressures is finally opening the pathway to practical superconductivity and its vast potential. Russell Hemley, a materials chemist at George Washington University in Washington, D.C., first announced evidence of superconductivity at 260 K in May, 2018, and then hints of an even higher 280 K transition in August of that year. Now Hemley, along with a team of researchers from The George Washington University and the Carnegie Institution for Science synthesized several lanthanum superhydride materials that demonstrated the first experimental evidence of superconductivity at near room temperature, and with colleagues from Argonne National Laboratory characterized them at the U.S. Department of Energy’s Advanced Photon Source (APS). Read more