Observation of the nonanalytic behavior of optical phonons in monolayer hexagonal boron nitride

Jiade Li, Li Wang, Yani Wang, Zhiyu Tao, Weiliang Zhong, Zhibin Su, Siwei Xue, Guangyao Miao, Weihua Wang, Hailin Peng, Jiandong Guo () and Xuetao Zhu ()
Additional contact information
Jiade Li: Chinese Academy of Sciences
Li Wang: Chinese Academy of Sciences
Yani Wang: Peking University
Zhiyu Tao: Chinese Academy of Sciences
Weiliang Zhong: Chinese Academy of Sciences
Zhibin Su: Chinese Academy of Sciences
Siwei Xue: Chinese Academy of Sciences
Guangyao Miao: Chinese Academy of Sciences
Weihua Wang: Chinese Academy of Sciences
Hailin Peng: Peking University
Jiandong Guo: Chinese Academy of Sciences
Xuetao Zhu: Chinese Academy of Sciences

Nature Communications, 2024, vol. 15, issue 1, 1-9

Abstract: Abstract Phonon splitting of the longitudinal and transverse optical modes (LO-TO splitting), a ubiquitous phenomenon in three-dimensional polar materials, will break down in two-dimensional (2D) polar systems. Theoretical predictions propose that the LO phonon in 2D polar monolayers becomes degenerate with the TO phonon, displaying a distinctive “V-shaped” nonanalytic behavior near the center of the Brillouin zone. However, the full experimental verification of these nonanalytic behaviors has been lacking. Here, using monolayer hexagonal boron nitride (h-BN) as a prototypical example, we report the comprehensive and direct experimental verification of the nonanalytic behavior of LO phonons by inelastic electron scattering spectroscopy. Interestingly, the slope of the LO phonon in our measurements is lower than the theoretically predicted value for a freestanding monolayer due to the screening of the Cu foil substrate. This enables the phonon polaritons in monolayer h-BN/Cu foil to exhibit ultra-slow group velocity (~5 × 10−6 c, c is the speed of light) and ultra-high confinement (~ 4000 times smaller wavelength than that of light). These exotic behaviors of the optical phonons in h-BN presents promising prospects for future optoelectronic applications.

Date: 2024
References: View references in EconPapers View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/s41467-024-46229-4 Abstract (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:natcom:v:15:y:2024:i:1:d:10.1038_s41467-024-46229-4

Ordering information: This journal article can be ordered from
https://www.nature.com/ncomms/

DOI: 10.1038/s41467-024-46229-4

Access Statistics for this article

Nature Communications is currently edited by Nathalie Le Bot, Enda Bergin and Fiona Gillespie

More articles in Nature Communications from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().