NONTRIVIAL MAGNETIC ORDER - LOCALIZED VERSUS ITINERANT SYSTEMS

The generalization of the non-Neel spin ordering concept to itinerant systems is discussed. It is shown that some of the p-type spin nematic and chiral spin states affect the electronic spectrum near the Fermi surface and can then be related by symmetry with the intrinsic instabilities of the Fermi liquid although the energetic mechanisms for the localized spins and itinerant electrons are different. If the localized and itinerant subsystems coexist, the phase transition is described by the common order parameter. Possible experimental manifestations of the above transitions are discussed.