Scanning Tunneling Microscopy Observation of Phonon Condensate
2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, 43214Article in journal (Refereed) Published
Using quantum tunneling of electrons into vibrating surface atoms, phonon oscillations can be observed on the atomic scale. Phonon interference patterns with unusually large signal amplitudes have been revealed by scanning tunneling microscopy in intercalated van der Waals heterostructures. Our results show that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance. The observed coherence of these quasi-bound states most likely arises from phase-and frequency-synchronized dynamics of all phonon modes, and indicates the formation of many-body condensate of optical phonons around resonant defects. We found that increasing the strength of the scattering resonance causes the increase of the condensate droplet radius without affecting the condensate fraction inside it. The condensate can be observed at room temperature.
Place, publisher, year, edition, pages
Nature Publishing Group, 2017. Vol. 7, 43214
IdentifiersURN: urn:nbn:se:kth:diva-204079DOI: 10.1038/srep43214ISI: 000394745200001PubMedID: 28225066ScopusID: 2-s2.0-85013956952OAI: oai:DiVA.org:kth-204079DiVA: diva2:1085456
QC 201703292017-03-292017-03-292017-03-29Bibliographically approved