Symmetry-protected nodal points and nodal lines in magnetic materials

Article

关键词: TOPOLOGICAL DIRAC SEMIMETAL;    NEUTRON-DIFFRACTION;    FERMIONS;    CATALOG;   

DOI  :  10.1103/PhysRevB.103.245141

来源: SCIE

【 摘 要 】

Nodal-point and nodal-line structures in the dispersion of electron energy bands are characterized by their high degeneracy in certain corners or lines in the Brillouin zone (BZ). These nodal structures can also exist in the dispersion of itinerant electrons in magnetically ordered materials whose symmetry groups are antiunitary groups called the magnetic space groups. In the present paper, we provide a complete list of magnetic space groups, which can host symmetry-protected nodal-point/line band structures for spin-1/2 fermionic particles, where the degeneracies at the nodal points/lines are guaranteed by irreducible projective representations (IPReps) of the little cogroups. Our discussion is restricted to the magnetic space groups whose magnetic point group contains the space-time inversion operation (T) over tilde = IT, the combined operation of spacial inversion I and time reversal T, such that the energy bands are at least doubly degenerate at arbitrary points in the BZ. For these magnetic point groups we provide the invariants to label the classes of projective Reps, and for each class we calculate all the inequivalent IPReps. From the results we select out all the groups and the corresponding Rep classes, which support high-dimensional (d >= 4) IPReps. We then list the magnetic space groups and their high-symmetry points/lines whose little cogroups have high-dimensional (d >= 4) IPReps with the corresponding factor systems. Examples of candidate materials are discussed.

【 授权许可】

Free