Quantum cascade of correlated phases in trigonally warped bilayer graphene
Quantum cascade of correlated phases in trigonally warped bilayer graphene
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DOI：
10.1038/s41586-022-04937-1
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发表时间：
2022-08-11
期刊：
影响因子：
64.8
通讯作者：
Weitz, R. Thomas
中科院分区：
文献类型：
--
作者：
Seiler, Anna M.;Geisenhof, Fabian R.;Weitz, R. Thomas
发散的态密度为探索各种相关的电子物理提供了机会。在最薄的极限下，这在魔角扭曲的双层石墨烯的超平能带(1-5)、少层菱面体石墨的带接触点(6-8)和轻掺杂的菱面体三层石墨烯(9-11)中得到了预测和验证。更简单和似乎更好理解的伯纳尔双层石墨烯在电荷中性(7)时也容易受到轨道磁性的影响，导致层反铁磁态(12)或量子反常霍尔态(13)。在这里，我们报道了在电场控制的Lifshitz跃迁(14，15)和van Hove奇点(16)附近观察到的级联关联相级联。我们为观察到半金属和四分之一金属(10，11)形式的斯通铁磁体提供了证据。此外，我们还发现了与零磁场下的非平凡维格纳-霍尔晶体(17)及其向平凡维格纳晶体的转变相一致的特征，以及两种相关的金属，它们的行为偏离了标准费米液体的行为。我们在这个可重复、可调谐、简单的系统中的结果为研究强关联电子开辟了新的视野。
Divergent density of states offers an opportunity to explore a wide variety of correlated electron physics. In the thinnest limit, this has been predicted and verified in the ultraflat bands of magic-angle twisted bilayer graphene(1-5), the band touching points of few-layer rhombohedral graphite(6-8) and the lightly doped rhombohedral trilayer graphene(9-11). The simpler and seemingly better understood Bernal bilayer graphene is also susceptible to orbital magnetism at charge neutrality(7) leading to layer antiferromagnetic states(12) or quantum anomalous Hall states(13). Here we report the observation of a cascade of correlated phases in the vicinity of electric-field-controlled Lifshitz transitions(14,15) and van Hove singularities(16) in Bernal bilayer graphene. We provide evidence for the observation of Stoner ferromagnets in the form of half and quarter metals(10,11). Furthermore, we identify signatures consistent with a topologically non-trivial Wigner-Hall crystal(17) at zero magnetic field and its transition to a trivial Wigner crystal, as well as two correlated metals whose behaviour deviates from that of standard Fermi liquids. Our results in this reproducible, tunable, simple system open up new horizons for studying strongly correlated electrons.