Kim Dohun, Jin Seyoung, Taniguchi Takashi, Watanabe Kenji, Smet Jurgen H, Cho Gil Young, Kim Youngwook
Department of Physics and Chemistry, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Republic of Korea.
Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea.
Nat Commun. 2025 Jan 2;16(1):179. doi: 10.1038/s41467-024-55486-2.
Magnetotransport of conventional semiconductor based double layer systems with barrier suppressed interlayer tunneling has been a rewarding subject due to the emergence of an interlayer coherent state that behaves as an excitonic superfluid. Large angle twisted bilayer graphene offers unprecedented strong interlayer Coulomb interaction, since both layer thickness and layer spacing are of atomic scale and a barrier is no more needed as the twist induced momentum mismatch suppresses tunneling. The extra valley degree of freedom also adds richness. Here we report the observation of fractional quantum Hall physics at 1/3 total filling for balanced layer population in this system. Monte Carlo simulations support that the ground state is also an excitonic superfluid but the excitons are composed of fractional rather than elementary charges. The observed phase transitions with an applied displacement field at this and other fractional fillings are also addressed with simulations. They reveal ground states with different topology and symmetry properties.
对于具有势垒抑制层间隧穿的传统半导体基双层系统的磁输运，由于出现了表现为激子超流体的层间相干态，一直是一个有价值的研究课题。大角度扭曲双层石墨烯提供了前所未有的强层间库仑相互作用，因为层厚度和层间距均为原子尺度，并且由于扭曲引起的动量失配抑制了隧穿，不再需要势垒。额外的谷自由度也增加了丰富性。在此我们报告了在该系统中平衡层填充时在总填充量的1/3处观察到分数量子霍尔物理现象。蒙特卡罗模拟支持基态也是激子超流体，但激子由分数电荷而非基本电荷组成。在该填充量和其他分数填充量下，施加位移场时观察到的相变也通过模拟进行了研究。它们揭示了具有不同拓扑和对称性质的基态。
