Title: $$\mathrm{^{239}Pu}$$ nuclear magnetic resonance in the candidate topological insulator $$\mathrm{PuB_4}$$

Abstract

In this article, we present a detailed nuclear magnetic resonance (NMR) study of $$\mathrm{^{239}Pu}$$ in bulk and powdered single-crystal plutonium tetraboride ($$\mathrm{PuB_4}$$), which has recently been investigated as a potential correlated topological insulator. This study constitutes the second-ever observation of the $$\mathrm{^{239}Pu}$$ NMR signal, and provides unique on-site sensitivity to the rich $$f$$-electron physics and insight into the bulk gaplike behavior in $$\mathrm{PuB_4}$$. The $$\mathrm{^{239}Pu}$$ NMR spectra are consistent with axial symmetry of the shift tensor showing for the first time that $$\mathrm{^{239}Pu}$$ NMR can be observed in an anisotropic environment and up to room temperature. The temperature dependence of the $$\mathrm{^{239}Pu}$$ shift, combined with a relatively long spin-lattice relaxation time ($$T_1$$), indicate that $$\mathrm{PuB_4}$$ adopts a nonmagnetic state with gaplike behavior consistent with our density functional theory calculations. The temperature dependencies of the NMR Knight shift and $$T_1^{1}$$ –microscopic quantities sensitive only to bulk states–imply bulk gaplike behavior confirming that $$\mathrm{PuB_4}$$ is a good candidate topological insulator. The large contrast between the $$\mathrm{^{239}Pu}$$ orbital shifts in the ionic insulator $$\mathrm{PuO_2} (\sim {+24.7 }\%)$$ and $$\mathrm{PuB_4} (\sim-0.5\%)$$ provides a new tool to investigate the nature of chemical bonding in plutonium materials.

Authors:

Dioguardi, A. P. ^[1]; Yasuoka, H. ^[2]; Thomas, S. M. ^[3]; Sakai, H. ^[4]; Cary, S. K. ^[3]; Kozimor, S. A. ^[3]; Albrecht-Schmitt, T. E. ^[5]; Choi, H. C. ^[3]; Zhu, J. -X. ^[3]; Thompson, J. D. ^[3]; Bauer, E. D. ^[3]; Ronning, F. ^[3]

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+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Leibniz Institute for Solid State and Materials Research (IFW) Dresden (Germany)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Max Planck Inst. for Chemical Physics of Solids, Dresden (Germany)
3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Japan Atomic Energy Agency, Tokai, Naka (Japan)
5. Florida State Univ., Tallahassee, FL (United States)

Publication Date:

Wed Jan 02 00:00:00 EST 2019

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Actinide Science & Technology (CAST); Florida State Univ., Tallahassee, FL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1566685

Alternate Identifier(s):

OSTI ID: 1489316

Grant/Contract Number:  

SC0016568

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review B

Additional Journal Information:

Journal Volume: 99; Journal Issue: 3; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

73 NUCLEAR PHYSICS AND RADIATION PHYSICS; nuclear; defects; mechanical behavior; corrosion; charge transport; superconductivity; magnetism and spin physics; separations; geophysics/geochemistry; materials and chemistry by design; synthesis (novel materials); synthesis (self-assembly); synthesis (predictive); synthesis (scalable processing)