关键词： 外尔半金属, 电场, 磁场, 能带结构

Abstract: Based on the low-energy effective hamiltonian model under the tight-binding approximation,the modulation of the electronic band structure of weyl semimetals by applied electric and/or magnetic fields is investigated.The results show that:when only the positive (negative) electric field is applied,the weyl points of system gradually move towards the boundary (center) of the brillouin zone with the increasing of the electric field strength,and when the electric field strength increases to a certain extent,the semimetal-semiconductor (insulator) transition can be relieazed;when only the magnetic field is applied,the weyl semimetal can form the discrete landau levels,the n=0 subband does not change with the increasing of magnetic length while the n≠0 subband gradually approaches the fermi level with the increasing of magnetic length,and the band gap between the conduction and valence bands with same indices gradually decrease;when the magnetic length remains unchanged,the weyl points of system gradually move towards the boundary (center) of the brillouin zone with the increasing of the positive (negative) electric field strength.Under the appropriate electric field,the n=0 subband can change from partially occupied valence band to first conduction band (fully occupied first valence band) and realize the semimetal-semiconductor or semimetal-insulator transitions.

Key words: weyl semimetal, electric field, magnetic field, band structure