Field-Selective Anomaly and Chiral Mode Reversal in Type-II Weyl Materials.
Field-Selective Anomaly and Chiral Mode Reversal in Type-II Weyl Materials.
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DOI：
10.1103/physrevlett.117.086401
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发表时间：
2016-04
影响因子：
8.6
通讯作者：
M. Udagawa;E. Bergholtz;E. Bergholtz
中科院分区：
文献类型：
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作者：
M. Udagawa;E. Bergholtz;E. Bergholtz
外尔费米子的三维凝聚态一般都有一个倾斜的色散，这与它们难以捉摸的高能亲戚形成了鲜明的对比，在这些亲戚中，洛伦兹不变性禁止倾斜，而二维石墨烯片的低能激发则禁止倾斜，无论是晶体对称还是粒子-空穴对称。最近，一些材料（MoTe_{2}、LaAlGe和WTe_{2}）被确定为所谓的II型外尔费米子的宿主，其色散是如此强烈地倾斜，以至于形成费米面，由此外尔节点成为连接电子和空穴袋的奇点。我们在这里预测，这些系统在磁场的存在下具有显着的性能。最突出的是，我们表明，手征异常的性质取决于至关重要的所施加的字段和倾斜之间的相对角度，并且反转不对称overtilting创建的手征模式的数量与正负斜率的不平衡。场选择性异常提供了一种新的磁光共振，提供了一种实验方法来检测隐藏的Weyl节点。
Three-dimensional condensed matter incarnations of Weyl fermions generically have a tilted dispersion-in sharp contrast to their elusive high-energy relatives where a tilt is forbidden by Lorentz invariance, and with the low-energy excitations of two-dimensional graphene sheets where a tilt is forbidden by either crystalline or particle-hole symmetry. Very recently, a number of materials (MoTe_{2}, LaAlGe, and WTe_{2}) have been identified as hosts of so-called type-II Weyl fermions whose dispersion is so strongly tilted that a Fermi surface is formed, whereby the Weyl node becomes a singular point connecting electron and hole pockets. We here predict that these systems have remarkable properties in the presence of magnetic fields. Most saliently, we show that the nature of the chiral anomaly depends crucially on the relative angle between the applied field and the tilt, and that an inversion-asymmetric overtilting creates an imbalance in the number of chiral modes with positive and negative slopes. The field-selective anomaly gives a novel magneto-optical resonance, providing an experimental way to detect concealed Weyl nodes.