Researchers at Uppsala University and other collaborators discovered a new two-dimensional quantum material in a study recently published in Nature. The breakthrough material, composed of atomically thin layers of cerium, silicon and iodine (CeSiI), marks the first time a two-dimensional material with heavy fermions has appeared.
"The electrons in CeSiI are 100 times more massive than those in ordinary materials. That's why they are called heavy fermions." "What's special about CeSiI is that this effective mass is anisotropic and depends on the direction in which the electrons move in the atomic layer," said Chin-ShenOng, one of the researchers at Uppsala University behind the study.
The study is the result of a collaboration between materials theory researchers at Uppsala University and researchers at Columbia University in the United States. For materials researchers at Uppsala University, the main problem is to theoretically study the quantum properties of electrons in materials.
The background and significance of heavy fermions
Heavy fermion compounds are a class of materials with extremely strong electron interactions. In the process, they move in coordinated motion in so-called quantum fluctuations. This interaction makes the electrons 100 or 1,000 times more massive than electrons in ordinary materials. These quantum fluctuations are thought to play an important role in many hitherto unexplained quantum phenomena, such as unconventional superconductivity (where electric current can pass through materials without losing energy) and magnetism.
Heavy fermion materials have been studied for decades, but until now the focus has been on materials in which atoms are tightly packed into three-dimensional structures. As early as the 1970s, researchers at Uppsala University began to focus on cerium-based materials and achieved great success.
However, the new material, synthesized in a Columbia University laboratory, is unique because it has a two-dimensional-like crystal structure with clear separation between the layers and a very thin atomic thickness. The layers, composed of layers of cerium, silicon and iodine (CeSiI), are the first two-dimensional material with heavy fermions.
"With this discovery, we now have a vastly improved materials platform with which to study relevant electronic structures. 2D materials are like Lego bricks. Our partners are already working on adding layers of other 2D materials to create a new material with tailored quantum properties," says Chin-ShenOng.
Compiled source: ScitechDaily