Iron Atoms Found Moving Inside the Earth’s Solid Inner Core, Affecting the Magnetic Field With Their Collective Motion

Experts have long known that the Earth's solid inner core is mostly iron, whose atoms are tightly held together by astronomically high pressures. New research has revealed that these atoms are not stationary but on the move.

Exploring the Collective Motion of Iron Atoms

In collaboration with experts from China, researchers from the University of Texas discovered that certain groupings of iron atoms in the inner core of the Earth can move about rapidly. These particles change their places in a split second while maintaining the underlying metallic structure of the iron in a type of movement known as "collective motion."

These findings were gathered from laboratory experiments and theoretical models, indicating that atoms in the inner core are more mobile than previously thought. The results can help explain the intriguing characteristics of the inner core, which have long mystified scientists.

It is impossible to directly sample the Earth's inner core due to its extremely high temperatures and pressures, so the researchers decided to recreate it in miniature in the laboratory. They took a small iron plate and shot it with a fast-moving projectile to do this. The collected data involving the temperature, pressure, and velocity was then put into an AI algorithm of atoms in the inner core.

Experts think iron atoms in the inner core are arranged in repeating hexagonal patterns. As described by study author Professor Jung-Fu Lin at the UT Jackson School of Geosciences, most computer models depicting the lattice dynamics of iron in the inner core show only a small number of atoms, mostly fewer than a hundred.

Using machine-learning computer models, they built up the atomic environment, creating a 'supercell' composed of 30,000 atoms to predict the properties of iron more reliably. At this supercell scale, the research team observed groups of atoms moving about and changing places while maintaining the overall hexagonal configuration.

Effects of the Rapid Atomic Movement

The new findings on the inner core activity at the atomic scale can help future researchers understand the production of energy and heat at this layer of the Earth and its relationship to the dynamics of the outer core. The results can also help shed light on the role played by the inner core in powering our planet's geodynamo, the process that generates the Earth's magnetic field. About half of the geodynamo energy generating the magnetic field can be attributed to the planet's inner core, with the outer core making up the rest.

Furthermore, the atomic movement also holds the key to understanding the seismic activities on Earth. As explained by co-lead author Youjun Zhang from Sichuan University, the study's findings can explain why seismic measurements of the inner core show a type of environment much softer and malleable than expected at extremely high pressures.

Seismologists discovered that the center of the Earth is soft like butter. They found that solid iron becomes surprisingly soft deep inside the Earth because the iron atoms in its inner core can move much more than they ever imagined. The increased movement makes the inner core less rigid and weaker against shear forces.