Long Room (EUA)

Quantum transition makes electrons behave as if they lack spin

Publicado em 14 novembro 2019

The common phase transitions are those that occur as a function of temperature variation. Ice changes phase to become liquid water at 0 degrees Celsius. Liquid water changes phase to become water vapor at 100 degrees Celsius. Similarly, magnetic materials become nonmagnetic at critical temperatures. However, there are also phase transitions that do not depend on temperature. They occur in the vicinity of absolute zero [-273.15 degrees Celsius] and are associated with quantum fluctuations.

A study involving experiments under extreme conditions, especially ultra-low temperatures and intense magnetic fields, and accompanied by theoretical interpretation of the experimental results explored this type of situation and investigated the quantum critical point manifested in a highly unusual transition.
Researcher - Valentina - Martelli - Julio - Larrea

Italian researcher Valentina Martelli and Peruvian Julio Larrea, both professors at the University of São Paulo Physics Institute (IF-USP) in Brazil, participated in the study, which is published in Proceedings of The National Academy of Sciences (PNAS).

The experimental part, led by Professor Silke Paschen, was conducted in the laboratories of the Vienna University of Technology (TUW) in Austria. The theoretical work was performed by a group led by Qimiao Si, Professor of Physics and Astronomy at Rice University in the United States.

Evidence - Points - Breakdown - Kondo - Effect

"We found and interpreted evidence of two successive quantum critical points associated with a double breakdown of the Kondo effect," Larrea told.

Named for Japanese physicist Jun Kondo (born 1930), the Kondo effect explains the formation of heavy fermions in metal compounds based on rare-earth elements. In these compounds, the electrons behave collectively owing to their strong correlation, forming a singlet (a collective of distinct particles that behave as a single particle), which can be represented as the coupling of the localized magnetic moment of the rare-earth ion with the conduction electron around it. 

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