Tracing development of the dendritic cell lineage.

Sighting of magnetic Majorana fermions? Quantum spin liquids—materials whose magnetic spins do not settle into order even at absolute zero temperature—have long captured the interest of physicists. A particularly lofty goal is finding a material that can be described by the so-called Kitaev spin model, a network of spins on a honeycomb lattice that harbors Majorana fermions as its excitations. Banerjee et al. present a comprehensive inelastic neutron scattering study of single crystals of the material a-RuCl 3 , which has been predicted to a host a Kitaev spin liquid. The unusual dependence of Edited by Stella Hurtley I N SC IENCE J O U R NA L S RESEARCH