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Abstract

The electrical resistance of a single crystal of PuTe has been measured up to ~25 GPa and as a function of temperature down to 1.3 K. At low pressure, the resistance R displays the expected activated behavior, i.e., an upturn at low temperature and a change of curvature at ~200 K as at ambient pressure. Surprisingly, the resistance at 1.5 K is enhanced by increasing pressure. For the NaCl phase, we propose a model where the conductivity s is composed of three contributions; a constant 0 K term s(0) as expected in a seInin1etal, the Mott's law s()exp-(T(O)/T)(1/4) indicating variable-range hopping conductivity below 100 K, and an exponential term exp( -E(g)/2k(B)T) due to a band gap. At 0.2 GPa, the activation energies T(o) and E(g) equal 23 meV and 0.185 eV, and increase up to 110 meV and ~ 0.4 eV at 4.2 GPa, respectively. As a possible origin of the Mott's law behavior, we suggest a mechanism of hopping conduction involving the 5f states of the Pu ions. Between 10.7 GPa and 12.7 GPa, R strongly decreases over the whole temperature range. We attribute this collapse to the NaCI-CsCI structural transition. This effect indicates a strong increase of the state density and is in agreement with theoretical predictions. Above 12.7 GPa, the upturn tends to disappear and the temperature variation of R progressively approaches that of a metal. Our data suggest a magnetic transition below 15 K in the CsCI phase.

Additional information

Authors: ICHAS V, JRC-Institute for Transuranium Elements, Karlsruhe (DE);GRIVEAU J.C, JRC-Institute for Transuranium Elements, Karlsruhe (DE);REBIZANT J, JRC-Institute for Transuranium Elements, Karlsruhe (DE);SPIRLET J.C, JRC-Institute for Transuranium Elements, Karlsruhe (DE)
Bibliographic Reference: An article published in: Physical Review B. Vol.63 (2001) pp. 045109-1 to 045109-7
Availability: An article published in: Physical Review B. Vol.63 (2001) pp. 045109-1 to 045109-7
Record Number: 200013363 / Last updated on: 2001-06-27
Category: PUBLICATION
Original language: en
Available languages: en