Extremely low-frequency phonon material and its temperature- and photo-induced switching effects. Issue 33 (17th August 2020)

• Record Type: Journal Article
• Authors: Yoshida, Takaya; Nakabayashi, Koji; Tokoro, Hiroko; Yoshikiyo, Marie; Namai, Asuka; Imoto, Kenta; Chiba, Kouji; Ohkoshi, Shin-ichi
• Is Part Of: Chemical science. Volume 11:Issue 33(2020)
• Page Start: 8989
• Page End: 8998
• Publication Date: 2020-08-17
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d0sc02605k
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Extremely low-frequency optical phonon mode in Rb-intercalated two-dimensional cyanide-bridged Co–W bimetal assembly and its temperature- and photo-induced switching effect. Abstract : Atomic vibrations due to stretching or bending modes cause optical phonon modes in the solid phase. These optical phonon modes typically lie in the frequency range of 10 2 to 10 4 cm −1 . How much can the frequency of optical phonon modes be lowered? Herein we show an extremely low-frequency optical phonon mode of 19 cm −1 (0.58 THz) in a Rb-intercalated two-dimensional cyanide-bridged Co–W bimetal assembly. This ultralow frequency is attributed to a millefeuille-like structure where Rb ions are very softly sandwiched between the two-dimensional metal–organic framework, and the Rb ions slowly vibrate between the layers. Furthermore, we demonstrate temperature-induced and photo-induced switching of this low-frequency phonon mode. Such an external-stimulation-controllable sub-terahertz (sub-THz) phonon crystal, which has not been reported before, should be useful in devices and absorbers for high-speed wireless communications such as beyond 5G or THz communication systems.