Clay emerges as a natural semiconductor

Vermiculite has long been used in insulation, construction, and environmental applications (like water purification and CO₂ capture); however, it had never been explored as a material for nanoelectronics or spintronics.

Now a team led by NTNU, in collaboration with the ESRF’s BM01, has successfully found that it can function as a 2D semiconductor. “Quantum technology is often associated with synthetic materials that have been developed in advanced, completely clean environments,” says Professor Jon Otto Fossum from NTNU’s Department of Physics. “We have found a naturally occurring clay material with sought-after properties for use in quantum technology,” he adds.

Schematics of intercalation of dimethyl sulfoxide into stacks of vermiculite nanosheets kept together by interlayer cations and their further delamination by osmotic swelling. Credits: Pacáková, B. et al. Naturally occurring 2D semiconductor with antiferromagnetic ground state, npj 2D Materials and Applications (2025). DOI: 10.1038/s41699-025-00561-5

Scientists looked into exfoliating the material, because it has a layered structure and resembles that of graphite, which is used to make graphene. Until now, no one had explored it as a 2D material since it is very difficult to delaminate.

With help of in-situ diffraction experiments, the researchers established the way to reduce the material to a few atomic layers and discovered that its exfoliated form reveals semiconducting and antiferromagnetic properties. Nanosheets also have a high surface to volume ratio, which makes it interact more with light or electric fields. Due to their size, nanosheets can be integrated into thin films.

Dmitry Chernyshov, scientist in charge of BM01, explains the importance of this single-layered form: “The discovery of an antiferromagnetic ground state of vermiculite was only possible with its exfoliated form; it opens a route towards potential applications that would also require single nanosheets of this layered material”.

600 million tons of vermiculite

The exfoliation procedure was carried out at NTNU and optimized in three consecutive experiments at BM01, where synchrotron X-ray diffraction experiments solved the structural characterization of this clay and helped to establish a technology protocol in-situ to make its functional exfoliated form.

Unlike synthetic semiconductors, vermiculite is widely available, inexpensive and environmentally friendly, with global reserves estimated at 600 million tons. “Because of these features, it could help create sustainable, scalable materials for nanoelectronics and quantum technologies”, concludes Barabara Pacáková, the first author of the paper.

Reference:

Pacáková, B. et al. Naturally occurring 2D semiconductor with antiferromagnetic ground state, npj 2D Materials and Applications (2025). DOI: 10.1038/s41699-025-00561-5

Text by Montserrat Capellas Espuny

Top image: Vermiculite is a widely available mineral.