Magnetic field and strain effects in Janus-like Weyl semimetals MoTeSe with four Weyl points

We suggest a new Janus-like Weyl semimetal (WSM) candidate MoTeSe with only four Weyl points (WPs) by alloying route from prototype Td-phase WSM MoTe2 with twelve WPs. The topological properties and topological responses under external uniform magnetic field B and strain of MoTeSe have been investigated by Wannier-function-based tight-binding Hamiltonian and first-principles method. Our calculations show WSM state is robust in a large B with the magnitude of order 10 meV and the separation distance of WPs can be effectively modulated by changing the direction and strength of B. The four WPs move away from the kz = 0 plane and the energy of WP changes parabolically with the increase of c-axial B. By contrast, the energy of WP varies linearly and approaches to the Fermi level with the increasing a-/b-axial B. We further consider the influence of in-plane B on the topological response of MoTeSe and reveal a more complex and diverse behavior. In addition, four-WP MoTeSe displays good robustness within the moderate strain and can be transit into other multi-node WSM or non-WSM under larger strain. Our findings provide an excellent few-node WSM platform for understanding the behavior of Weyl fermion under external magnetic or strain field and a potential candidate for applications of WSM in topological electronic devices.