Speaker
Matthias Graf
(LANL)
Description
We present first-principles based multiband spin-fluctuation
calculations within the random-phase approximation for four
isostructural intermetallic actinides, namely the
superconductors PuCoIn5, PuCoGa5, PuRhGa5, and the
paramagnet UCoGa5. The results show that a strong peak in
the spin-fluctuation dressed self-energy is present around
0.5 eV in all materials, which is mostly created by 5f
electrons. These fluctuations are coupled to electrons,
which gives rise to the peak-dip-hump structure in the
spectral function, characteristic of the coexistence of
itinerant and localized electronic states. Our results are
in quantitative agreement with available photoelectron
spectra on PuCoGa5 [1] and UCoGa5 [2].
Our self-consistent intermediate Coulomb coupling GW
calculations of the self-energy are performed within the
fluctuation exchange approximation [3,4] using
first-principles electronic structure input obtained from
the density functional theory within the generalized
gradient approximation (GGA). We find that the effective
coupling of electrons to spin fluctuations creates a dip in
the single-particle excitations due to strong scattering
between spin-orbit split states. The lost spectral weight
(dip) in the spectral function is distributed partially to
the renormalized itinerant states at the Fermi level (peak),
as well as to the strongly localized incoherent states at
higher energy (hump). The coherent states at the Fermi level
can still be characterized as Bloch waves, though strongly
renormalized, whereas the incoherent electrons are localized
in real space exhibiting the dispersionless hump structure.
We will discuss the impact of our first-principles based
intermediate coupling model for calculating electronic hot
spots in the spectral function and the multiband
spin-fluctuation spectrum relevant for electric and thermal
transport in both actinide metals and nuclear fuel materials.
This work was supported by the U.S. DOE under Contract No.
DE-AC52-06NA25396 through the Office of Basic Energy
Sciences (BES) and the LDRD Program at LANL. We acknowledge
a NERSC computing allocation of the U.S. DOE under Contract
No. DE-AC02-05CH11231.
[1] T. Das, J.-X. Zhu, and M.J. Graf (2012), Phys. Rev. Lett. 108, 137001.
[2] T. Das, T. Durakiewicz, J.-X. Zhu, J.J. Joyce, J. L. Sarrao, and M.J. Graf (2012), Phys. Rev. X 2, 041012.
[3] R.S. Markiewicz, T. Das, S. Basak, and A. Bansil (2010), J. Electron. Spectrosc. Relat. Phenom. 181, 23.
[4] T. Das, J.-X. Zhu, and M.J. Graf (2013), J. Materials Research 28, 659.
[1] T. Das, J.-X. Zhu, and M.J. Graf (2012), Phys. Rev. Lett. 108, 137001.
[2] T. Das, T. Durakiewicz, J.-X. Zhu, J.J. Joyce, J. L. Sarrao, and M.J. Graf (2012), Phys. Rev. X 2, 041012.
[3] R.S. Markiewicz, T. Das, S. Basak, and A. Bansil (2010), J. Electron. Spectrosc. Relat. Phenom. 181, 23.
[4] T. Das, J.-X. Zhu, and M.J. Graf (2013), J. Materials Research 28, 659.
