Field-induced magnetization of <i>δ</i>-plutonium from density functional theory

We present results from density functional theory (DFT) calculations of magnetization, induced by an external magnetic field, for \ensuremath{\delta}-phase plutonium. The fully relativistic electronic structure accounts for Zeeman splitting effects through a Hamiltonian that couples the magnetic field to both spin and orbital magnetic moments. The electronic-structure model is further improved by an extension to DFT in terms of an orbital-orbital coupling via the conventional orbital-polarization method, as has routinely been done for plutonium. The response to the applied magnetic field is shown to be weak in the DFT model, with induced magnetic moments of the order of ${10}^{\ensuremath{-}3}\phantom{\rule{0.16em}{0ex}}{\textmu{}}_{\mathrm{B}}$ in magnetic fields up to 30 T. These results are in accord with recent assessments from x-ray magnetic circular dichroism measurements in magnetic field on \ensuremath{\delta}-plutonium. Somewhat surprisingly, a model assuming \ensuremath{\delta}-plutonium to be absent magnetic moments shows stronger response to an external static magnetic field than models allowing for antiferromagnetism or magnetic disorder.