Ligand and actinide NMR studies in actinide oxides and intermetallic compounds

Abstract

In this paper we present highlights from a 6-year program of NMR/NQR/AFNMR studies carried out on both actinide and ligand nuclear spins in oxides and intermetallic compounds of the actinide elements U, Np, and Pu. We begin with the large family of actinide 115 compounds, consisting of metallic antiferromagnets, metamagnets, Pauli paramagnets, and the superconducting Pu-based systems. Short summaries are presented of 69,71Ga NMR studies of the exotic metamagnet NpCoGa 5, the surprisingly inhomogeneous UCoGa 5, and the heavy-fermion "high-T c" superconductors PuTGa 5, T = Rh and Co. The case of microdomains in the metallic antiferromagnet UGa 3 is briefly reviewed. Next, we summarize the direct and indirect 235U NMR studies on USb 2 and URh 3. These are the first studies of their kind and the only studies of 235U NMR in a metallic environment. Under the heading of actinide oxides we recap our original studies of 235U and 17O NMR in UO 2, followed by a summary of our investigation of multipolar ordering in NpO 2 via 17O NMR, in which the 237Np NMR parameters were determined via cross-relaxation effects. And finally, we summarize our 31P study of the ferromagnetic transition in the filled Skutterudite UFe 4P 12. ©2007 The Physical Society of Japan.