Magnetism at Earth’s core: Simulations offer breakthrough insights
The Earth’s magnetic field is essential for life. It shields the planet from cosmic radiation and solar wind. While scientists understand the basic mechanisms, many details remain unresolved.
To investigate, a new simulation method has been developed by researchers from the Center for Advanced Systems Understanding (CASUS) at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Sandia National Laboratories, and the French Alternative Energies and Atomic Energy Commission (CEA).
This simulation method offers fresh insights into the structure of Earth’s core and supports innovations in technology.
Computer simulations of Earth’s core
The Earth’s magnetic field is generated by the geodynamo effect.
“We know that the Earth’s core is primarily composed of iron,” noted Attila Cangi, Head of the Machine Learning for Materials Design Department at CASUS.
As you move closer to the core, pressure and temperature increase. The outer core remains molten, while the inner core stays solid due to these conditions.
Electrically charged, liquid iron flows around the solid core. These flows are driven by Earth’s rotation, as well as by convection currents, which generate electric currents that produce the magnetic field.
However, scientists still face questions. What is the core’s exact structure? Do additional elements besides iron influence the geodynamo effect? Seismic wave experiments provide some clues. These waves travel through Earth and are measured using sensitive sensors.
“These experiments suggest that the core contains more than just iron,” said Svetoslav Nikolov from Sandia National Laboratories. “The measurements do not agree with computer simulations that assume a pure iron core.”
Shock waves and Earth’s magnetic field
To address these questions, the research team developed a remarkable simulation method called “molecular-spin dynamics.” This method integrates two previously separate approaches:
- Molecular dynamics – models atomic motion.
- Spin dynamics – accounts for magnetic properties.
“By combining these two methods, we were able to investigate the influence of magnetism under high-pressure and high-temperature conditions on length and time scales that were previously unattainable,” stated CEA physicist Julien Tranchida.
The team simulated the behavior of two million iron atoms and their magnetic spins. They analyzed how mechanical and magnetic properties interact under extreme pressure and temperature conditions.
Artificial intelligence played a crucial role. The researchers used machine learning to determine precise force fields, which define how atoms interact. High-performance computing resources enabled this level of accuracy.
Results from the simulations
Once the models were ready, the team simulated Earth’s core conditions. They propagated pressure waves through the iron atoms, mimicking the heating and compression deep inside Earth.
When the shock waves were slower, the iron remained solid and formed different crystal structures. Faster shock waves turned the iron mostly liquid. The findings revealed significant effects of magnetism on material properties.
“Our simulations agree well with the experimental data,” said Mitchell Wood, a materials scientist at Sandia National Laboratories. “They suggest that under certain temperature and pressure conditions, a particular phase of iron could stabilize and potentially affect the geodynamo.”
This phase, called the bcc phase, has not been experimentally observed in such conditions. It has only been hypothesized. If confirmed, this discovery could resolve key questions about how Earth’s magnetic field forms.
Energy-efficient AI systems
The research extends beyond understanding Earth’s core. The new simulation method could advance materials science and technology. Cangi aims to use this technique to model neuromorphic computing devices.
Neuromorphic computing is inspired by the human brain’s functioning. It promises faster, energy-efficient AI processing. By simulating spin-based neuromorphic systems, the team’s method could drive innovative hardware development.
Additionally, the method may revolutionize data storage. Magnetic domains on tiny nanowires could serve as future storage media. These systems would be faster and more efficient than current technologies.
“There are currently no accurate simulation methods for either application,” said Cangi. “But I am confident that our new approach can model the required physical processes in such a realistic way, that we can significantly accelerate the technological development of these IT innovations.”
Future simulations of Earth’s core
This breakthrough offers a powerful tool for geophysics and materials science. Understanding the Earth’s core remains vital for answering fundamental questions about our planet’s magnetic field.
At the same time, the method’s potential in neuromorphic computing and advanced storage systems could transform future technologies. As researchers refine these simulations, they move closer to solving the mysteries of Earth’s magnetic field and driving innovations in AI and IT.
The new molecular-spin dynamics method represents a step forward for both geoscience and technology. Whether solving Earth’s mysteries or building energy-efficient AI, its impact promises to be far-reaching.
The study is published in the journal Proceedings of the National Academy of Sciences.
Image Credit: B. Schröder/ HZDR/ NASA/ Goddard Space Flight Center Scientific Visualization Studio
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