SPIN FLUCTUATIONS IN (Y0.97SC0.03)MN-2 - A GEOMETRICALLY FRUSTRATED, NEARLY ANTIFERROMAGNETIC, ITINERANT-ELECTRON SYSTEM

Inelastic neutron-scattering experiments have been performed on a sing le crystal of (Y0.97Sc0.03)Mn-2. The spin fluctuation spectrum is broa d in energy and strongly correlated in wave vector, with maximum inten sity at the Brillouin zone boundary. There is no magnetic scattering f or Brillouin zones centered at the origin and at certain reciprocal la ttice points, suggesting the existence of short-lived 4-site collectiv e spin singlets. The unusual features of the dynamical susceptibility discovered in this. experiment result from geometrical frustration and give new insight into the heavy-fermion-like behavior of the compound .