Spectroscopic Evidence for a Spin- and Valley-Polarized Metallic State in a Nonmagic-Angle Twisted Bilayer Graphene

In the magic-angle twisted bilayer graphene (MA-TBG), strong electron-electron (e-e) correlations caused by the band-flattening lead to many exotic quantum phases such as superconductivity, correlated insulator, ferromagnetism, and quantum anomalous Hall effects, when its low-energy van Hove singularities (VHSs) are partially filled. Here our high-resolution scanning tunneling microscope and spectroscopy measurements demonstrate that the e-e correlation in a nonmagic-angle TBG with a twist angle θ = 1.49° still plays an important role in determining its electronic properties. Our most interesting observation on that sample is when one of its VHSs is partially filled, the one associated peak in the spectrum splits into four peaks. Simultaneously, the spatial symmetry of electronic states around the split VHSs is broken by the e-e correlation. Our analysis based on the continuum model suggests that such a one-to-four split of the VHS originates from the formation of an interaction-driven spin-valley-polarized metallic state near the VHS, which is a symmetry-breaking phase that has not been identified in the MA-TBG or in other systems.

Medienart:

E-Artikel

Erscheinungsjahr:

2020

Erschienen:

2020

Enthalten in:

Zur Gesamtaufnahme - volume:14

Enthalten in:

ACS nano - 14(2020), 10 vom: 27. Okt., Seite 13081-13090

Sprache:

Englisch

Beteiligte Personen:

Ren, Ya-Ning [VerfasserIn]
Lu, Chen [VerfasserIn]
Zhang, Yu [VerfasserIn]
Li, Si-Yu [VerfasserIn]
Liu, Yi-Wen [VerfasserIn]
Yan, Chao [VerfasserIn]
Guo, Zi-Han [VerfasserIn]
Liu, Cheng-Cheng [VerfasserIn]
Yang, Fan [VerfasserIn]
He, Lin [VerfasserIn]

Links:

Volltext

Themen:

Electron−electron correlations
Journal Article
Moiré superlattices
Scanning tunneling microscopy/spectroscopy
Spin and valley polarization
Twisted bilayer graphene

Anmerkungen:

Date Revised 30.10.2020

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1021/acsnano.0c04631

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM316223107