Oxygen, the colorless and odorless gas that is essential to the survival of humans and other living organisms, is estimated to make up around 21% of Earth’s atmosphere. While the primary properties of oxygen are now well understood, the states that can emerge in it at extreme conditions (e.g., at high pressures) are still under investigation.

Researchers at Shanghai Advanced Research in Physical Sciences (SHARPS), the Center for High Pressure Science and Technology Advanced Research in China, the Italian National Institute of Optics of the National Council of Research (CNR-INO), the European Synchrotron Radiation Facility and University Montpellier carried out a study exploring the properties of a high–pressure phase of solid oxygen, known as epsilon oxygen (ε-O₂).

Their paper, published in Physical Review Letters, offers the first indirect evidence that a dynamic magnetic state, known as a spin-liquid state, emerges in epsilon oxygen.