Magnetic ordering in the fine particles of some bulk Pauli paramagnets

Abstract

Fine particles of some of the extensively studied 'enhanced' Pauli paramagnets, LuCo₂, ScCo₂, ZrCo₂, and CeRu₂Si₂, have been prepared by high-energy ball milling and investigated for their magnetic behaviors. In the case of Co systems, these particles show ferromagnetic features even at room temperature. Even in the case of CeRu₂Si₂, a well-known Kondo lattice which is nonmagnetic in the bulk form, features attributable to the onset of magnetic order below about 8 K could be seen in fine particles. The magnitudes of the magnetic moment of these small particles at high fields are sufficiently large to conclude that the observed magnetic ordering is not just a surface effect. This transformation to magnetic ordering in small particles could be widespread among enhanced Pauli paramagnets.