Extreme infrared laser pulses reveal frozen electron waves

Posted Mar 19, 2020 by Tim Sandle
Scientists have deployed extreme infrared laser pulses to unlock frozen electron waves in magnetite, which is generally regarded as the world's oldest magnetic material. This solves a long-standing puzzle in physics.
Artist s impression of the core of a laser-ignited hydrogen-boron fusion reactor.
Artist's impression of the core of a laser-ignited hydrogen-boron fusion reactor.
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Through the new research, scientists from the Massachusetts Institute of Technology have successfully confirmed the existence of electronic waves in magnetite, using a red laser beam. These waves are frozen at a transition temperature of 125 kelvins (-148.15 Celsius) and at this temperature the electrons start “dancing together” (as the researchers describe the pattern). The dancing takes the form of collective oscillating motions as the temperature is lowered.
Magnetite (chemical formula: Fe3O4, also called lodestone, or magnetic iron ore) is a rock mineral and one of the main iron ores. It is one of just a few minerals that are attracted to a common magnet, and widely considered to be the first magnetic material to be discovered on Earth. One of the applications of magnetite is with specific gravity separations (an industrial method of separating two components).
A long-standing mystery with magnetite is with how the material transforms from a metal to an insulator. The new research, using sophisticated laser technology (called ultrafast terahertz spectroscopy), shows how the atoms shift to a new lattice structure, and this results in a shift with the complicated ordered pattern. This shift is referred to as the Verwey transition. By ultrafast this means moving at a rate of one millionth of one millionth of a second.
The use of ultra-short laser pulses has revealed what is happening with the electronic waves within magnetite as temperatures lowers (these cause the displacement of the surrounding atoms), which explains, for the first time, the shift to the material becoming an insulator.
The research is published in the science journal Nature, where the research paper is titled "Discovery of the soft electronic modes of the trimeron order in magnetite."