2023-08-04 13:45:03
Many substances change their properties when cooled below a certain critical temperature. Such a phase transition occurs, for example, when water freezes. However, in certain metals there are phase transitions on a microscopic scale that do not exist in the macrocosm. They arise due to the special laws of quantum mechanics that prevail in the realm of the smallest building blocks of nature.
It has been suspected that the traditional concept of electrons as electric charge carriers is not applicable near some exotic phase transitions. Now, some scientists have verified that the suspicion is true.
These scientists are from the University of Bonn in Germany and the Swiss Federal Institute of Technology in Zurich (ETH).
Electrons can be locked in atoms, without being able to get out of them if the situation remains stable. Some electrons in metals, on the other hand, move freely, not confined to a particular atom, which is why these metals can also conduct electricity.
In certain exotic quantum materials, both varieties of electrons can form a superposition state. This produces what are known as quasiparticles. They are, in a sense, immobile and mobile at the same time, a characteristic that is only possible in the quantum world.
These quasiparticles, unlike “normal” electrons, can be destroyed during a phase transition. This means that in those cases the properties of a continuous phase transition can also be observed.
Artist’s impression of a quasiparticle, made up of electrons attached to an atom and free electrons, which is broken by the action of an ultra-short pulse of light. (Illustration: University of Bonn)
This phenomenon had only been observed indirectly, in some experiments.
Now a team consisting of, among others, Hans Kroha from the Bethe Center for Theoretical Physics at the University of Bonn, as well as Chia-Jung Yang and Manfred Fiebig from the Swiss Federal Institute of Technology in Zurich, has devised a new method that allows the direct identification of the collapse of electron quasiparticles in a phase transition.
The progress achieved in this study will contribute to a better understanding of phase transitions in the quantum world.
The study is titled “Critical slowing down near a magnetic quantum phase transition with fermionic breakdown”. And it has been published in the academic journal Nature Physics. (Source: NCYT from Amazings)
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