Title : The Valence-Fluctuating Ground State of Plutonium

A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such electronic correlations frequently arise due to the competition of localized and itinerant electronic degrees of freedom. While the respective limits of well-localized or entirely itinerant ground states are well-understood, the intermediate regime that controls the functional properties of complex materials continues to challenge theoretical understanding. We have used neutron spectroscopy to investigate plutonium, which is a prototypical material at the brink between bonding and non-bonding configurations. Our study reveals that the ground state of plutonium is governed by valence fluctuations, that is, a quantum-mechanical superposition of localized and itinerant electronic configurations as recently predicted by dynamical mean field theory. Our results not only resolve the long-standing controversy between experiment and theory on plutonium’s magnetism, but also suggest an improved understanding of the effects of such electronic dichotomy in complex materials.

[1]  M. Baskes,et al.  Atomistic modeling of thermodynamic properties of Pu-Ga alloys based on the Invar mechanism , 2014 .

[2]  E. Bauer,et al.  Q-dependence of the spin fluctuations in the intermediate valence compound CePd3 , 2014, Journal of physics. Condensed matter : an Institute of Physics journal.

[3]  D. L. Wang,et al.  Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics , 2012, Proceedings of the National Academy of Sciences.

[4]  D. Pines,et al.  Emergent states in heavy-electron materials , 2012, Proceedings of the National Academy of Sciences.

[5]  Jiao Y. Y. Lin,et al.  Design and operation of the wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source. , 2012, The Review of scientific instruments.

[6]  G. Laan,et al.  Valence fluctuations in thin films and the α and δ phases of Pu metal determined by 4f core-level photoemission calculations , 2010 .

[7]  T. Allen,et al.  The solubility of hydrogen and deuterium in alloyed, unalloyed and impure plutonium metal , 2010 .

[8]  Kristjan Haule,et al.  Dynamical mean-field theory within the full-potential methods: Electronic structure of CeIrIn 5 , CeCoIn 5 , and CeRhIn 5 , 2009, 0907.0195.

[9]  Chris Hooley,et al.  The strong-correlations puzzle , 2009 .

[10]  F. Trouw,et al.  Pu neutron scattering studies – Magnetism and structure , 2009 .

[11]  G. Laan,et al.  Nature of the 5f states in actinide metals , 2008, 0807.0416.

[12]  G. Kotliar,et al.  Fluctuating valence in a correlated solid and the anomalous properties of δ-plutonium , 2007, Nature.

[13]  M. McElfresh,et al.  Emergent magnetic moments produced by self-damage in plutonium , 2006, Proceedings of the National Academy of Sciences.

[14]  E. Bauer,et al.  Limits for ordered magnetism in Pu from muon spin rotation spectroscopy , 2006 .

[15]  C. Marianetti,et al.  Electronic structure calculations with dynamical mean-field theory , 2005, cond-mat/0511085.

[16]  J. Taylor,et al.  Magnetic form factor of alpha-Ce: towards understanding the magnetism of cerium. , 2005, Physical review letters.

[17]  G. Lander,et al.  Absence of Magnetic Moments in Plutonium , 2004, cond-mat/0410634.

[18]  T. M. Kelley,et al.  Unusual phonon softening in delta-phase plutonium. , 2004, Physical review letters.

[19]  J. Betts,et al.  Experimental electronic heat capacities of alpha- and delta-plutonium: heavy-fermion physics in an element. , 2003, Physical review letters.

[20]  Z. Fisk,et al.  Inelastic neutron scattering in single-crystal YbInCu 4 , 1997 .

[21]  A. Hewson.  The Kondo Problem to Heavy Fermions: Preface , 1993 .

[22]  Y. Kuramoto,et al.  Analytic results on dynamics of the degenerate Anderson model , 1985 .

[23]  J. L. Smith,et al.  Magnetism or bonding: A nearly periodic table of transition elements , 1983 .

[24]  V. Pecharsky,et al.  Handbook on the physics and chemistry of rare earths , 1979 .

[25]  R. Birgeneau,et al.  Spin dynamics in the mixed valence alloy Ce/sub 1ts-tsx/Th/sub x/ , 1977 .

[26]  A. Blaise,et al.  The magnetic susceptibility of Americium and curium metal , 1975 .

[27]  J. Schrieffer,et al.  Relation between the Anderson and Kondo Hamiltonians , 1966 .

[28]  Philip W. Anderson,et al.  Localized Magnetic States in Metals , 1961 .