![]() ![]() ![]() ![]() The NMR shift provides direct information about the s- and d-electron contributions to the density of states DOS at the Fermi level E F, whereas the spin lattice relaxation provides information about the low energy excitations onto s- and d-electrons around E F. Magnetic resonance has (in contrast to neutron scattering) a large potential as a local probe for linear d- electron bands. Furthermore pronounced quantum oscillations of hole and electron bands could be observed and, due to the moderate spin-orbit interaction, these Landau bands are spin-splitted. As a consequence, Weyl fermions show unconventional electron and heat transport phenomena. The density of states (DOS) for Dirac- and Weyl-SMs exhibits an unconventional energy-dependence with N(E) ~ E 2 which is in contrast to conventional metals where N(E) ~ E 1/2 is valid. Furthermore due to the spin orbit coupling the Weyl fermions have a chirality on their linear dispersive bands. ![]() In contrast to the topological insulators where a linear dispersion is found on the surface in WSM this dispersion is found in the bulk. The hallmark of Weyl semimetals is the formation of pairs of Weyl points in reciprocal space and their linear dispersion relation leading to mass less fermions when the Fermi energy crosses exactly the Weyl points. Compensated d-electron semimetals (SM) like the monophosphites NbP and TaP, with non centrosymmetric structure and sizable spin orbit interaction (few tens meV) form a new class of material: the Weyl semimetals (WSM). ![]()
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