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Journal Articles

New surprises "down below"; Recent successes in the synthesis of actinide materials

Sarrao, J. L.*; Haga, Yoshinori; Ward, R. C. C.*

MRS Bulletin, 35(11), p.877 - 882, 2010/11

https://doi.org/10.1557/mrs2010.714
 Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)

Journal Articles

Influence of self-irradiation on the magnitude of the superfluid density in PuCoGa$$_5$$ probed by muon spin rotation

Oishi, Kazuki; Heffner, R. H.; Ito, Takashi; Higemoto, Wataru; Morris, G. D.*; Bauer, E. D.*; Graf, M. J.*; Zhu, J.-X.*; Morales, L. A.*; Sarrao, J. L.*; et al.

Physica B; Condensed Matter, 403(5-9), p.1013 - 1014, 2008/04

https://doi.org/10.1016/j.physb.2007.10.079
 Times Cited Count：0 Percentile：0.00(Physics, Condensed Matter)

PuCoGa$$_5$$ has attracted much interest because it is the first Pu-based superconductor, having an order of magnitude higher transition temperature $$T_{rm c}=18.5$$K than the isostructural heavy fermion superconductor CeCoIn$$_5$$ ($$T_{rm c}=2.3$$K). The mechanism of the superconductivity in PuCoGa$$_5$$ is still under investigation, though recent experiments and theory suggest a magnetic origin. A unique aspect of this compound is the self-irradiation damage because Pu ($$^{239}$$Pu, $$T^{1/2}$$ = 24,000 years) creates lattice defects which scatter electrons and, hence, break superconducting pairs. In order to elucidate the magnitude and temperature dependence of the magnetic penetration depth $$lambda$$, we have performed $$mu$$SR measurements in the same PuCoGa$$_5$$ single crystals after 25 and 400 days of aging. We found that $$T_{rm c}$$ decreased from 18.5K to 15K for the aged sample, yet a quasi-linear temperature dependence was found for the low-temperature $$lambda(T)$$ in both the fresh and aged sample, consistent with $$d$$-wave pairing symmetry. The magnitude of the muon spin relaxation rate $$sigma$$ in the aged sample, $$sigmapropto 1/lambda^2proptorho_s/m^*$$, where $$rho_s$$ and $$m^*$$ are the superfluid density and the effective mass, respectively, is reduced by about 70% compared to fresh sample. This indicates that the scattering from self-irradiation induced defects is not in the limit of the conventional Abrikosov-Gor'kov pair-breaking theory, but rather in the limit of short coherence length (about 2nm in PuCoGa$$_5$$) superconductivity.

Journal Articles

$$mu$$SR study of the effects of Ce dilution on the development of the heavy-fermion state in (Ce,La)$$_2$$IrIn$$_8$$

Oishi, Kazuki; Heffner, R. H.; Ito, Takashi; Higemoto, Wataru; Morris, G. D.*; Hur, N.*; Bauer, E. D.*; Sarrao, J. L.*; Thompson, J. D.*; MacLaughlin, D. E.*; et al.

Journal of Physics and Chemistry of Solids, 68(11), p.2068 - 2071, 2007/11

https://doi.org/10.1016/j.jpcs.2007.08.045
 Times Cited Count：2 Percentile：12.81(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

The Search for magnetic order in $$delta$$-Pu metal using muon spin relaxation

Heffner, R. H.; Oishi, Kazuki; Fluss, M. J.*; Morris, G. D.*; MacLaughlin, D. E.*; Shu, L.*; Chung, B. W.*; McCall, S. K.*; Bauer, E. D.*; Sarrao, J. L.*; et al.

Journal of Alloys and Compounds, 444-445, p.80 - 83, 2007/10

https://doi.org/10.1016/j.jallcom.2006.12.026
 Times Cited Count：9 Percentile：47.73(Chemistry, Physical)

We summarize the results of muon spin relaxation ($$mu$$SR) measurements carried out in$$alpha$$- and $$delta$$-Pu and in the superconducting state ofPuCoGa$$_5$$. In Pu metal, interest has centered on whether or not magnetic order exists in the hightemperature fcc $$delta$$ phase,The Pu metal studies were designed to search for evidence of magnetic ordering, andhave set the most stringent limits to date for the ordered moment. In PuCoGa$$_5$$ the temperature dependence of themagnetic penetration depth $$lambda$$(T) was investigated in a fresh sample and again in the same sampleafter 400 days of aging. We find $$lambda$$(T)$$propto$$ T for T $$<$$ Tc/2, indicating a line of nodes in thesuperconducting order parameter. Remarkably, the temperature dependence of $$lambda$$(T) is littlechanged even after significant radiation damage.

Journal Articles

Muon spin rotation measurements of the superfluid density in fresh and aged superconducting PuCoGa$$_5$$

Oishi, Kazuki; Heffner, R. H.; Morris, G. D.*; Bauer, E. D.*; Graf, M. J.*; Zhu, J.-X.*; Morales, L. A.*; Sarrao, J. L.*; Fluss, M. J.*; MacLaughlin, D. E.*; et al.

Physical Review B, 76(6), p.064504_1 - 064504_10, 2007/08

https://doi.org/10.1103/PhysRevB.76.064504
 Times Cited Count：13 Percentile：50.92(Materials Science, Multidisciplinary)

Journal Articles

Magnetic penetration depth and self-induced irradiation effects in superconducting PuCoGa$$_5$$ probed by muon spin rotation

Oishi, Kazuki; Heffner, R. H.; Morris, G. D.*; Fluss, M. J.*; Bauer, E. D.*; Morales, L. A.*; Sarrao, J. L.*; MacLaughlin, D. E.*; Shu, L.*; Ito, Takashi; et al.

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.566 - 568, 2007/03

no abstracts in English

Journal Articles

$$mu$$SR studies of Pu metal and the Pu-based superconductor PuCoGa$$_5$$

Heffner, R. H.; Bauer, E. D.*; Chung, B.*; Fluss, M. J.*; Higemoto, Wataru; Ito, Takashi; MacLaughlin, D. E.*; Morales, L. A.*; Morris, G. D.*; Oishi, Kazuki; et al.

Journal of the Physical Society of Japan, 75(Suppl.), p.14 - 19, 2006/08

no abstracts in English

Journal Articles

$$mu$$SR studies of the superconducting order parameter in PuCoGa$$_5$$

Morris, G. D.*; Heffner, R. H.; Bauer, E. D.*; Morales, L. A.*; Sarrao, J. L.*; Fluss, M. J.*; MacLaughlin, D. E.*; Shu, L.*; Anderson, J. E.*

Physica B; Condensed Matter, 374-375, p.180 - 183, 2006/03

https://doi.org/10.1016/j.physb.2005.11.047
 Times Cited Count：15 Percentile：55.45(Physics, Condensed Matter)

Journal Articles

Evolution of the heavy fermion state in Ce$$_2$$IrIn$$_8$$

Heffner, R. H.; Morris, G. D.*; Bauer, E. D.*; Sarrao, J. L.*; Thompson, J. D.*; MacLaughlin, D. E.*; Shu, L.*

Physica B; Condensed Matter, 375-375, p.184 - 187, 2006/03

https://doi.org/10.1016/j.physb.2005.11.048
 Times Cited Count：6 Percentile：30.40(Physics, Condensed Matter)

Journal Articles

Limits for ordered magnetism in Pu from muon spin rotation spectroscopy

Heffner, R. H.; Morris, G. D.*; Fluss, M. J.*; Chung, B.*; McCall, S.*; MacLaughlin, D. E.*; Shu, L.*; Oishi, Kazuki; Bauer, E. D.*; Sarrao, J. L.*; et al.

Physical Review B, 73(9), p.094453_1 - 094453_5, 2006/03

https://doi.org/10.1103/PhysRevB.73.094453
 Times Cited Count：35 Percentile：77.20(Materials Science, Multidisciplinary)

no abstracts in English

Oral presentation

Superconductivity and magnetism in T$$_n$$M$$_m$$In$$_{3n+2m}$$

Oishi, Kazuki; Heffner, R. H.; Ito, Takashi; Higemoto, Wataru; Morris, G. D.*; Hur, N.*; Bauer, E. D.*; Sarrao, J. L.*; Thompson, J. D.*; MacLaughlin, D. E.*; et al.

no journal, , 

no abstracts in English

Oral presentation

Knight shift measurements in Ce$$_2$$Rh(In,Sn)$$_8$$ probed by $$mu$$SR

Oishi, Kazuki; Heffner, R. H.; Ito, Takashi; Higemoto, Wataru; Morris, G. D.*; Hur, N.*; Bauer, E. D.*; Sarrao, J. L.*; Thompson, J. D.*; MacLaughlin, D. E.*; et al.

no journal, , 

no abstracts in English

Oral presentation

$$mu$$SR measurements on the superconducting penetration depth in aged PuCoGa$$_5$$

Heffner, R. H.; Oishi, Kazuki; Higemoto, Wataru; Ito, Takashi; Morris, G. D.*; Fluss, M. J.*; MacLaughlin, D. E.*; Shu, L.*; Bauer, E. D.*; Sarrao, J. L.*

no journal, , 

The superconductor PuCoGa$$_{5}$$ possesses a relatively high critical temperature (T$$_{c}$$ = 18.5 K), a moderate mass enhancement (Sommerfeld coefficient $$cong $$ 80 mJ/mol-K$$^{2})$$ and exhibits behavior consistent with spin-fluctuation-induced d-wave superconductivity. It is also radioactive, with its dominant radioisotope $$^{239}$$Pu having a half-life of 2.4 $$times$$ 10$$^{4}$$ yrs. We report $$mu $$SR measurements of the temperature and field dependence of the magnetic field penetration depth $$lambda $$(T,H) in a 400 day-old sample of PuCoGa$$_{5}$$ (T$$_{c}$$ = 15 K), and compare these results to data obtained on the same sample approximately one year earlier. In 600 Oe applied field both measurements show a linear low-temperature behavior for $$lambda $$(T) - $$lambda $$(0) = bT for T/T$$_{c} quad <$$ 0.5 with the same coefficient b. The magnitude of $$lambda $$(0) in the aged sample has increased by a factor of about 1.8. The results are discussed in terms of the effects of radiation damage on the postulated d-wave superconducting order parameter.

Oral presentation

Effects of the La substitution on the heavy fermion state in (Ce,La)$$_2$$IrIn$$_8$$

Oishi, Kazuki; Heffner, R. H.; Ito, Takashi; Higemoto, Wataru; Morris, G. D.*; Bauer, E. D.*; Sarrao, J. L.*; Thompson, J. D.*; MacLaughlin, D. E.*; Shu, L.*

no journal, , 

no abstracts in English

Oral presentation

Quasiparticle excitations in PuCoGa$$_5$$ probed by muon spin rotation

Oishi, Kazuki; Heffner, R. H.; Higemoto, Wataru; Ito, Takashi; Morris, G. D.*; Bauer, E. D.*; Morales, L. A.*; Sarrao, J. L.*; Fluss, M. J.*; MacLaughlin, D. E.*; et al.

no journal, , 

The discovery of the first Pu-based superconductor PuCoGa$$_{5}$$ ($$T_c$$ = 18.5 K) demonstrates the rich and complex nature of Pu-based materials. The mechanism of the superconductivity in PuCoGa$$_{5}$$ is still under investigation, though recent experiments and theory suggest a magnetic origin. For example, the electronic structure of this material was investigated theoretically, and spin-fluctuation mediated superconductivity was suggested. NMR results also suggest that the superconducting order parameter of this Pu-based superconductor has d-wave symmetry. We note that Pu is a radioactive nucleus ($$^{239}$$Pu, $$T^{1/2}$$ = 24000 years), thus PuCoGa$$_{5}$$ suffers self-induced radiation damage. Previous $$mu$$SR results performed at 600 Oe in a 25-day old single crystalline sample show a linear temperature dependence for the muon spin relaxation rate $$sigma$$ ($$propto lambda^{-2}$$, $$lambda$$: magnetic penetration depth) for $$T/T_cle$$ 0.5, suggesting d-wave pairing symmetry. We have performed $$mu$$SR experimentes on the same sample after 400 days of aging in order to obtain more detailed information on the order parameter, i.e., T-dependence of $$lambda$$ at several magnetic fields, as well as the effects of aging. We found that Tc decreased from 18.5 K to 15 K for the 25-day and 400-day samples, respectively, yet the linear temperature dependence remains, consistent with a line of nodes (and suggesting d-wave pairing symmetry). These results indicate that the temperature dependence of $$lambda$$ does not depend on accumulated radiation damage over the span of time measured.

Oral presentation

Knight shift measurements in (Ce,La)$$_2$$IrIn$$_8$$ probed by $$mu$$SR, 2

Oishi, Kazuki; Heffner, R. H.; Ito, Takashi; Higemoto, Wataru; Morris, G. D.*; Hur, N.*; Bauer, E. D.*; Sarrao, J. L.*; Thompson, J. D.*; MacLaughlin, D. E.*; et al.

no journal, , 

no abstracts in English

Oral presentation

Muon spin rotation measurements of the superfluid density in fresh and aged superconducting PuCoGa$$_5$$

Heffner, R. H.; Oishi, Kazuki; Higemoto, Wataru; Ito, Takashi; Morris, G. D.*; Bauer, E. D.*; Graf, M. J.*; Sarrao, J. L.*; Fluss, M. J.*; MacLaughlin, D. E.*; et al.

no journal, , 

no abstracts in English

17 (Records 1-17 displayed on this page)
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