All known elementary particles can be sorted into two categories: bosons and fermions. Bosons carry forces, like the magnetic force or gravity, while fermions are the matter particles, like electrons. Theoretically it was predicted that fermions themselves can come in three species, named after the physicists Dirac, Weyl, and Majorana.
Electrons in free space are Dirac fermions, but in solids they can change their nature. In the atomically thin carbon material graphene they become massless Dirac fermions. In other recently discovered and manufactured materials, they can also become Weyl and Majorana fermions, which makes such materials interesting for future technologies such as topological quantum computers and other novel electronic devices.
In combination with a wave of bosons, namely photons in a laser, fermions can be transformed from one type to another, as proposed by MPSD theorists in 2016 (see ref. 1) below). Now a new study led by PhD student Gabriel Topp in the Emmy Noether group of Michael Sentef suggests that electron spins can be manipulated by short light pulses to create a magnetic version of Weyl fermions from a magnetic insulator. Based on a prior study led by MPSD postdoctoral researcher Nicolas Tancogne-Déjean and Theory Director Angel Rubio (see ref. 2 below), the scientists used the idea of laser-controlled electron-electron repulsion to suppress magnetism in a pyrochlore iridate material where electron spins are positioned on a lattice of tetrahedra.
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