Unusual field-induced transition in a frustrated itinerant antiferromagnet

A model that includes instability of the magnetic moment in a frustrated lattice has recently been proposed for R${\mathrm{Mn}}_2$ systems (R=rare earth). An ordered mixed phase induced by a magnetic field in which magnetic and nonmagnetic sites coexist has been predicted by Monte Carlo simulations. The existence of this transition is now confirmed by a neutron-diffraction study of ${\mathrm{TbMn}}_2$ in a magnetic field.