霍夫施塔特区域中磁场诱导的外尔节点成对湮灭
Pairwise annihilation of Weyl nodes induced by magnetic fields in the Hofstadter regime
AI总结：
本研究探究霍夫施塔特区域全范围磁场诱导的外尔节点成对湮灭效应，明确了不同外尔节点配置下湮灭后生成的物相类型，提出了可准确预测湮灭后物相的直观表征方法。
摘要：
外尔半金属是三维量子物质中一种稳定的无隙态，除平移对称性外无需其他对称性保护。当平移对称性保持时，破坏外尔半金属态的唯一方式是使两个手性相反的外尔节点相互靠近并发生成对湮灭。当磁长度$l_B$接近或小于动量空间间距的倒数$1/2k_0$时，外磁场可破坏一对动量空间间距为$2k_0$的手性相反外尔节点。本研究探究了霍夫施塔特区域$l_B \sim a$下，磁场强度从小到大覆盖全范围时，外磁场诱导的外尔节点成对湮灭现象。我们证明，含两个外尔节点的外尔半金属中发生这种成对湮灭后，会形成普通绝缘体或层状陈绝缘体；对于含多个外尔节点的外尔半金属，可通过外磁场诱导生成多种不同物态。本研究提出了一种简洁直观的磁场诱导外尔节点成对湮灭过程表征方法，可准确预测外尔节点成对湮灭后可能出现的物相。
英文摘要：
Weyl semimetal, which does not require any symmetry except translation for protection, is a robust gapless state of quantum matters in three dimensions. When translation symmetry is preserved, the only way to destroy a Weyl semimetal state is to bring two Weyl nodes of opposite chirality close to each other to annihilate pairwise. An external magnetic field can destroy a pair of Weyl nodes (which are separated by a momentum space distance $2k_0$) of opposite chirality, when the magnetic length $l_B$ becomes close to or smaller than the inverse separation $1/2k_0$. In this work, we investigate pairwise annihilation of Weyl nodes induced by external magnetic field which ranges all the way from small to a very large value in the Hofstadter regime $l_B \sim a$. We show that this pairwise annihilation in a WSM featuring two Weyl nodes leads to the emergence of either a normal insulator or a layered Chern insulator. In the case of a Weyl semimetal with multiple Weyl nodes, the potential for generating a variety of states through external magnetic fields emerges. Our study introduces a straightforward and intuitive representation of the pairwise annihilation process induced by magnetic fields, enabling accurate predictions of the phases that may appear after pairwise annihilation of Weyl nodes.
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