Correlated insulating and superconducting states in twisted bilayer graphene below the magic angle

被引：163

作者：

Codecido, Emilio ^{[1
]}

Wang, Qiyue ^{[2
]}

Koester, Ryan ^{[1
]}

Che, Shi ^{[1
]}

Tian, Haidong ^{[1
]}

Lv, Rui ^{[1
]}

Tran, Son ^{[1
]}

Watanabe, Kenji ^{[3
]}

Taniguchi, Takashi ^{[3
]}

Zhang, Fan ^{[2
]}

Bockrath, Marc ^{[1
]}

Lau, Chun Ning ^{[1
]}

机构：

[1] Ohio State Univ, Dept Phys, 174 W 18th Ave, Columbus, OH 43210 USA

[2] Univ Texas Dallas, Dept Phys, Richardson, TX 75080 USA

[3] Natl Inst Mat Sci, 1-1 Namiki, Tsukuba, Ibaraki 3050044, Japan

来源：

SCIENCE ADVANCES | 2019年 / 5卷 / 09期

关键词：

DIRAC FERMIONS; MOIRE BANDS;

D O I：

10.1126/sciadv.aaw9770

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

The emergence of flat bands and correlated behaviors in "magic angle" twisted bilayer graphene (tBLG) has sparked tremendous interest, though its many aspects are under intense debate. Here we report observation of both superconductivity and the Mott-like insulating state in a tBLG device with a twist angle of similar to 0.93 degrees, which is smaller than the magic angle by 15%. At an electron concentration of +/- 5 electrons/moire unit cell, we observe a narrow resistance peak with an activation energy gap similar to 0.1 meV. This indicates additional correlated insulating state, and is consistent with theory predicting a high-energy flat band. At doping of +/- 12 electrons/moire unit cell we observe resistance peaks arising from the Dirac points in the spectrum. Our results reveal that the "magic" range of tBLG is in fact larger than what is previously expected, and provide a wealth of new information to help decipher the strongly correlated phenomena observed in tBLG.

引用

页数：5

共 45 条

[1] Moire bands in twisted double-layer graphene [J].