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arXiv 1902.04264cond-mat.mes-hall
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平凡带中的非平凡量子振荡几何相移

Non-trivial quantum oscillation geometric phase shift in a trivial band

Biswajit Datta, Pratap Chandra Adak, Li-kun Shi, Kenji Watanabe, Takashi Taniguchi, Justin C. W. Song, Mandar M. Deshmukh

摘要:

材料响应中非平凡几何相的积累通常是丰富的潜在内部结构的一个明显迹象。研究量子振荡提供了确定这些几何相位的方法之一,例如在拓扑量子材料中发挥核心作用的Berry相位。我们报告在ABA-三层石墨烯,其中的能带结构的磁输运测量是由一个弱带隙的线性狄拉克带,嵌套在平凡的二次带。在这里,我们显示Shubnikov-de Haas(SdH)振荡的二次带移动的相位,急剧偏离预期的2 $π$贝瑞的相位。我们的分析表明,令人惊讶的是,异常的相移是非平凡的,是继承自非平凡的Berry相位的线性狄拉克带由于强填充强制约束之间的线性和二次带费米面。鉴于许多拓扑材料包含多个频带,我们的工作表明如何额外的频带,这被认为是模糊的分析,实际上可以利用梳理出贝瑞的相位的微妙影响。

英文摘要:

The accumulation of non-trivial geometric phases in a material's response is often a tell-tale sign of a rich underlying internal structure. Studying quantum oscillations provides one of the ways to determine these geometrical phases, such as Berry's phase, that play a central role in topological quantum materials. We report on magneto-transport measurements in ABA-trilayer graphene, the band structure of which is comprised of a weakly gapped linear Dirac band, nested within a trivial quadratic band. Here we show Shubnikov-de Haas (SdH) oscillations of the quadratic band shifted by a phase that sharply departs from the expected 2$π$ Berry's phase. Our analysis reveals that, surprisingly, the anomalous phase shift is non-trivial and is inherited from the non-trivial Berry's phase of the linear Dirac band due to strong filling-enforced constraints between the linear and quadratic band Fermi surfaces. Given that many topological materials contain multiple bands, our work indicates how additional bands, which are thought to obscure the analysis, can actually be exploited to tease out the subtle effects of Berry's phase.

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