Electronic structure and magnetic properties of dilute U impurities in metals

• Published in: Journal of magnetism and magnetic materials Vol. 405; pp. 107 - 116
• Main Authors: Mohanta, S.K., Cottenier, S., Mishra, S.N.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2016
• Subjects: 5f impurity; Ab initio calculation; Electronic structure; Hyperfine structure; Impurities; Local magnetic moment; Magnetic moment; Magnetism; Mathematical models; Orbitals; Uranium; Ab initio calculation; 5f impurity; Local magnetic moment
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2015.12.042

The electronic structure and magnetic moment of dilute U impurity in metallic hosts have been calculated from first principles. The calculations have been performed within local density approximation of the density functional theory using Augmented plane wave+local orbital (APW+lo) technique, taking account of spin–orbit coupling and Coulomb correlation through LDA+U approach. We present here our results for the local density of states, magnetic moment and hyperfine field calculated for an isolated U impurity embedded in hosts with sp-, d- and f-type conduction electrons. The results of our systematic study provide a comprehensive insight on the pressure dependence of 5f local magnetism in metallic systems. The unpolarized local density of states (LDOS), analyzed within the frame work of Stoner model suggest the occurrence of local moment for U in sp-elements, noble metals and f-block hosts like La, Ce, Lu and Th. In contrast, U is predicted to be nonmagnetic in most transition metal hosts except in Sc, Ti, Y, Zr, and Hf consistent with the results obtained from spin polarized calculation. The spin and orbital magnetic moments of U computed within the frame of LDA+U formalism show a scaling behavior with lattice compression. We have also computed the spin and orbital hyperfine fields and a detail analysis has been carried out. The host dependent trends for the magnetic moment, hyperfine field and 5f occupation reflect pressure induced change of electronic structure with U valency changing from 3+ to 4+ under lattice compression. In addition, we have made a detailed analysis of the impurity induced host spin polarization suggesting qualitatively different roles of f-band electrons on moment stability. The results presented in this work would be helpful towards understanding magnetism and spin fluctuation in U based alloys. •We studied the electronic structure and magnetism of U impurity in metallic hosts.•Investigated host dependence of U-5f moment formation in s, p, d and f block metals.•Pressure dependence of U-5f spin and orbital moments is illustrated.•Observed lattice pressure induced valence transition.