Swiss researchers have described a strange phenomenon at the atomic scale, involving seemingly indivisible electrons that can exhibit an exotic behavior in which they "split" into two separate entities.

Electrons can be thought of as small magnets carrying negative electrical charge, two properties that on a fundamental level are considered indivisible.

However, in certain materials where the electrons are constrained in materials so thin they can be considered a quasi one-dimensional world -- materials such as nanowires -- electrons can appear to "split" into a magnet and an electrical charge, referred to as "fractional particles," which can move freely and independently of each other.

Scientists have long debated whether a similar phenomenon can occur in more than one dimension; now a research team led by scientists at the Ecole Polytechnic Fédérale de Lausanne has found evidence showing this can happen in quasi two-dimensional magnetic materials.

Writing in the journal Nature Physics, EPFL scientists have reported both theoretical and experimental evidence suggesting this exotic splitting of electrons into fractional particles can indeed take place in two dimensions.

Nobel laureate P.W. Anderson first put such a possibility forward in 1987 as part of a theory attempting to explain high-temperature superconductivity, in which electrons can flow in a material with zero resistance.

The EPFL researchers used state-of-the-art polarized neutron scattering technology to test a material that normally acts as an electrical insulator, and found that the electrons' magnetic moment can split into two halves and move almost independently in the material.

In the search for materials that display high-temperature superconductivity, understanding of the splitting phenomenon on a fundamental level has been a challenge, the researchers say, so their work represents support for the superconductivity theory put forward by Anderson.

"This work marks a new level of understanding in one of the most fundamental models in physics," says EPFL researcher Henrik M. Rønnow. "It also lends new support for Anderson's theory of high-temperature superconductivity, which, despite twenty-five years of intense research, remains one of the greatest mysteries in the discovery of modern materials."

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