What is it about?

In this study, we exposed different crystals belonging to the family of high-temperature superconducting cuprates to ultrashort laser light pulses. We observed how some of the materials began to emit a particular type of terahertz (THz) light – a technique known as THz emission spectroscopy. Usually, such emission only occurs in the presence of a magnetic field or polarizing current. However, we probed the cuprates without applying any external bias and discovered ‘anomalous’ THz emission in some of them. Those compounds featured the so-called charge-stripe order, a peculiar ordered phase which is believed to play a role in the mechanism underlying high-temperature superconductivity. Charge stripes are likely to cause a symmetry breaking in the superconductor, the presence of which had not been found by other experimental techniques in the past.

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Why is it important?

Our work provides important new insights into the processes leading to high-temperature superconductivity. It also reveals coherent anomalous THz emission as a sensitive tool to probe the symmetry of superconductors in the presence of other phases. We feel it should be applied to a wider class of compounds in the future, opening up new possibilities for understanding the physics of complex interactions in these materials.


Based on our results, the study of coherent anomalous terahertz emission emerges as a sensitive tool to probe the symmetry of superconductors in the presence of frustrated couplings, which is a key topic in the physics of these materials.

Daniele Nicoletti
Max Planck Institute for the Structure and Dynamics of Matter

Read the Original

This page is a summary of: Coherent emission from surface Josephson plasmons in striped cuprates, Proceedings of the National Academy of Sciences, September 2022, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2211670119.
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