  We study dilute magnetic impurities and vacancies in two-dimensional
frustrated magnets with non-collinear order. Taking the triangular-lattice
Heisenberg model as an example, we use quasiclassical methods to determine the
impurity contributions to the magnetization and susceptibility. Most
importantly, each impurity moment is not quantized, but receives non-universal
screening corrections due to local relief of frustration. At finite
temperatures, where bulk long-range order is absent, this implies an
impurity-induced magnetic response of Curie form, with a prefactor
corresponding to a fractional moment per impurity. We also discuss the behavior
in an applied magnetic field, where we find a singular linear-response limit
for overcompensated impurities, and propose experiments to test our theory.
