New State of Matter Found in Earth's Inner Core

Scientists have unveiled a groundbreaking discovery at Earth's center, identifying a new superionic state of matter within the planet's solid inner core. This revelation, reported on December 10, 2025, by ScienceDaily, indicates that carbon atoms move freely through a solid iron lattice, fundamentally altering our understanding of Earth's deepest layer.

This unusual behavior causes the inner core to be surprisingly soft, a characteristic that has long puzzled geophysicists studying seismic observations. The findings, published in the National Science Review, provide a compelling explanation for these long-standing anomalies.

The research suggests that the inner core is not a conventional solid, but rather a dynamic hybrid where light elements behave like a liquid within a stable iron framework. This "superionic phase" dramatically reduces the rigidity of the iron-carbon alloy, according to Professor Youjun Zhang of Sichuan University.

Furthermore, the mobility of these light elements within the core may play a crucial role in generating Earth's magnetic field. Dr. Yuqian Huang, also from Sichuan University, noted that atomic diffusion within the inner core represents a previously overlooked energy source for the geodynamo.

The investigation was spearheaded by Professor Zhang and Dr. Huang from Sichuan University, alongside Professor Yu He from the Institute of Geochemistry, Chinese Academy of Sciences. Their collaborative efforts have reshaped existing models of our planet's interior, as detailed by vertexaisearch.cloud.google.com.

To achieve this breakthrough, researchers replicated the extreme conditions of the inner core in laboratory settings. They combined in-situ sound velocity measurements with advanced molecular dynamics simulations, observing a significant decrease in shear wave speed, as reported by scitechdaily.

This discovery not only resolves decades-old seismic mysteries but also carries profound implications for understanding the magnetic and thermal evolution of other rocky planets and exoplanets. As Professor Zhang highlighted, this moves scientists away from a static model toward a more dynamic view of planetary interiors.

• For decades, Earth's inner core, a dense sphere primarily composed of iron and nickel, was believed to be a conventional solid due to immense pressure, despite its scorching temperatures comparable to the Sun's surface. However, seismic data consistently showed it behaving like a softened metal, slowing shear waves and exhibiting a Poisson's ratio more akin to butter than steel, according to Science China Press.
• The superionic state is an exotic phase of matter where one component forms a solid crystalline lattice, while another component, typically lighter elements like carbon, hydrogen, or oxygen, diffuses through it with liquid-like mobility. In Earth's inner core, carbon atoms flow freely through a solid iron framework, as explained by researchers from the Chinese Academy of Sciences.
• The "softness" paradox of the inner core has been a long-standing enigma. Seismic waves, generated by earthquakes, travel through the Earth's interior, and their behavior provides clues about the composition and state of different layers. The unexpectedly low shear wave velocity observed in the inner core is now directly explained by this superionic behavior, according to a study cited by SciTechDaily.
• The dynamic movement of light elements within the superionic inner core is believed to be a significant contributor to Earth's magnetic field, or geodynamo. Dr. Huang emphasized that this atomic diffusion represents a previously overlooked energy source, complementing heat and compositional convection in powering our planet's protective magnetic engine.
• The research team employed a sophisticated methodology, including dynamic shock compression experiments that propelled iron-carbon samples to extreme conditions, reaching pressures up to 140 gigapascals and temperatures near 2,600 Kelvin. These experimental results were then combined with advanced molecular dynamics simulations to confirm the superionic phase, as detailed by vertexaisearch.cloud.google.com.
• The concept of a superionic state in Earth's core isn't entirely new; computer simulations in 2022 had already suggested this exotic form, involving hydrogen, oxygen, and carbon. However, experimental confirmation under conditions accurately replicating the inner core proved challenging until this recent breakthrough, as reported by Live Science.
• This discovery has far-reaching implications beyond our planet, potentially enhancing our understanding of the magnetic and thermal evolution of other rocky planets and exoplanets. Professor Zhang noted that identifying a superionic phase in Earth's core brings scientists closer to unlocking the secrets of Earth-like planetary interiors across the cosmos.
• The shift from a static, rigid model to a dynamic one for the inner core opens new avenues for future research into Earth's internal processes. Scientists will continue to investigate how this superionic state influences phenomena like seismic anisotropy and the long-term stability and fluctuations of Earth's magnetic field, according to scitechdaily.