Merging of momentum-space monopoles by controlling magnetic field: From cubic-Dirac to triple-Weyl fermion systems

• Main Author: Ezawa, Motohiko
• Format: Text
• Language: unknown
• Published: arXiv 2017
• Subjects: Mesoscale and Nanoscale Physics cond-mat.mes-hall; Materials Science cond-mat.mtrl-sci; Quantum Gases cond-mat.quant-gas; High Energy Physics - Theory hep-th; FOS Physical sciences; South Pole; North Pole; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.1705.07690; https://arxiv.org/abs/1705.07690

We analyze a generalized Dirac system, where the dispersion along the $k_{x}$ and $k_{y}$ axes is $N$-th power and linear along the $k_{z}$ axis. When we apply magnetic field, there emerge $N$ monopole-antimonopole pairs beyond a certain critical field in general. As the direction of the magnetic field is rotated toward the $z$ axis, monopoles move to the north pole while antimonopoles move to the south pole. When the magnetic field becomes parallel to the $z$ axis, they merge into one monopole or one antimonopole whose monopole charge is $\pm N$. The resultant system is a multiple-Weyl semimetal. Characteristic properties of such a system are that the anomalous Hall effect and the chiral anomaly are enhanced by $N$ times and that $N$ Fermi arcs appear. These phenomena will be observed experimentally in the cubic-Dirac and triple-Weyl fermion systems ($N=3$). : 5 pages, 3 figures