Observation of second sound in a rapidly varying temperature field in Ge

Albert Beardo, Miquel Lopez-Suarez, Luis Alberto Perez, Lluc Sendra, Maria Isabel Alonso, Claudio Melis, Javier Bafaluy, Juan Camacho, Luciano Colombo, Riccardo Rurali, Francesc Xavier Alvarez, Juan Sebastian Reparaz*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

19 Citations (Scopus)


Second sound is known as the thermal transport regime where heat is carried by temperature waves. Its experimental observation was previously restricted to a small number of materials, usually in rather narrow temperature windows. We show that it is possible to overcome these limitations by driving the system with a rapidly varying temperature field. High-frequency second sound is demonstrated in bulk natural Ge between 7 K and room temperature by studying the phase lag of the thermal response under a harmonic high-frequency external thermal excitation and addressing the relaxation time and the propagation velocity of the heat waves. These results provide a route to investigate the potential of wave-like heat transport in almost any material, opening opportunities to control heat through its oscillatory nature.

Original languageEnglish
Article number4677
Number of pages6
JournalScience advances
Issue number27
Publication statusPublished - Jun 2021




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