Nonreciprocal transmission in composite structure with Weyl semimetal defect layer

A two-unit symmetrical composite structure with the WSMs defect layer was designed. The energy band and transmission properties are studied based on the transfer matrix theory. Due to the WSMs with the property of time-reversal breaking, the nonreciprocal Tamm states for forward and backward incidence are excited in the interface of the symmetrical composite structure. The numerical results show that the nonreciprocity of the Tamm states is enhanced with an increase in the WSMs thickness. By choosing the appropriate geometric parameters of dielectric layers, two pairs of nonreciprocal dispersive curves are obtained in the two-band gap. The present scenario can be applied in some areas, such as optical isolators and multi-channel nonreciprocal transmission devices.