Tomonaga-Luttinger Liquid in MoSe₂ Twin Domain Boundaries

In epitaxial MoSe₂ monolayer grown by molecular-beam epitaxy, dense networks of twin domain boundaries (DBs) have been observed [1]. They behave as metals. Being sandwiched between semiconducting pristine MoSe₂ domains, they represent an ideal one-dimensional (1D) system for studying the physics of 1D metals, such as the Peierls type instability and collective excitations of Tomonaga-Luttinger liquid (TLL). Indeed, there have already been reports of charge density waves (CDW) [2] and the TLL [3] in such systems. In this work, we report a low-temperature scanning tunneling spectroscopy study revealing the quantum confinement effect and signatures of the TLL in the 4|4P-type DB defects in MoSe₂. Notably, CDW is not observed at temperatures down to ~ 5 K. This finding is consistent with a recent study of another type (4|4E) 1D defect in MoS₂ [4].

[1] H. Liu et al., Physical Review Letters 113, 066105 (2014)
[2] S. Barja et al., Nature Physics 12, 751 (2016)
[3] Y. Ma et al., Nature communications 8, 14231 (2017)
[4] W. Jolie et al., Physical Review X 9, 011055 (2019)