Nodal points of Weyl semimetals survive the presence of moderate disorder
Nodal points of Weyl semimetals survive the presence of moderate disorder
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DOI：
10.1103/physrevb.98.205134
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发表时间：
2018-11-19
影响因子：
3.7
通讯作者：
Altland, Alexander
中科院分区：
文献类型：
--
作者：
Buchhold, Michael;Diehl, Sebastian;Altland, Alexander
在这项工作中，我们解决了物理学的个别三维Weyl节点受到适度浓度的混乱。先前的分析表明存在量子相变，低于该相变，无序变得无关紧要，并且在该系统中保留了消失的谱密度的尖锐节点的完整性。这种说法似乎与统计上罕见的波动的不可避免的存在不一致，这种波动不能被认为是弱的，并且必须对系统的光谱产生强烈的影响，无论平均浓度有多小。在这里，我们调和这两个图片表明，在Weyl系统中的罕见的波动势产生一种特殊类型的共振进行频谱密度在任何附近的零能量，但从来没有在零。以这种方式，弱无序的DoS的消失在包含罕见事件之后幸存下来。我们证明了这一特点，考虑三种不同的模型的障碍，每个强调特定方面的问题：一个简单的盒子潜在的模型，高斯分布的障碍，和一个有限数量的s波散射体。我们的分析还解释了为什么节点DoS的保护可能很难在有限大小的晶格模拟中看到。
In this work we address the physics of individual three-dimensional Weyl nodes subject to a moderate concentration of disorder. Previous analysis indicates the presence of a quantum phase transition below which disorder becomes irrelevant and the integrity of sharp nodal points of vanishing spectral density is preserved in this system. This statement appears to be at variance with the inevitable presence of statistically rare fluctuations which cannot be considered as weak and must have strong influence on the system's spectrum, no matter how small the average concentration. We here reconcile the two pictures by demonstrating that rare fluctuation potentials in the Weyl system generate a peculiar type of resonances which carry spectral density in any neighborhood of zero energy, but never at zero. In this way, the vanishing of the DoS for weak disorder survives the inclusion of rare events. We demonstrate this feature by considering three different models of disorder, each emphasizing specific aspects of the problem: a simplistic box potential model, a model with Gaussian distributed disorder, and one with a finite number of s-wave scatterers. Our analysis also explains why the protection of the nodal DoS may be difficult to see in simulations of finite size lattices.