Charge Density Modulation and the Luttinger Liquid State in MoSe<sub>2</sub> Mirror Twin Boundaries.

Xia, Yipu; Zhang, Junqiu; Jin, Yuanjun; Ho, Wingkin; Xu, Hu; Xie, Maohai · ACS Nano · 2020

basic_science · Level V

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Abstract

A mirror twin-domain boundary (MTB) in monolayer MoSe<sub>2</sub> represents a (quasi) one-dimensional metallic system. Its electronic properties, particularly the low-energy excitations in the so-called 4|4P-type MTB, have drawn considerable research attention. Reports of quantum well states, charge density waves, and the Tomonaga-Luttinger liquid (TLL) have all been made. Here, by controlling the lengths of the MTBs and employing different substrates, we reveal by low-temperature scanning tunneling microscopy/spectroscopy, Friedel oscillations and quantum confinement effects causing the charge density modulations along the defect. The results are inconsistent with charge density waves. Interestingly, for graphene-supported samples, TLL in the MTBs is suggested, whereas that grown on gold, an ordinary Fermi liquid, is indicated.