Thermal expansion of the heavy-fermion superconductor 
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Eloirdi, R.; Giacobbe, Carlotta; Celdran, P. Amador; Magnani, N.; Lander, G. H.; Griveau, J.‐C.; Colineau, E.; Miyake, Kazumasa; Caciuffo, R.

doi:10.1103/physrevb.95.094517

Cited by 10 publications

(6 citation statements)

References 26 publications

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“…As an example of a high resolution XRD study, we show in Fig. 8 the results obtained for the PuCoGa 5 unconventional superconductor (Eloirdi et al, 2017). The experiment was performed at the ESRF ID22 beamline, affording a resolution ∆d/d = 10 −6 at λ = 0.354155 Å.…”

Section: B High Intensity and Resolutionmentioning

confidence: 99%

“…The shrinking of the cell volume is similar to the one observed for the CeRu 2 Si 2 Kondo system (Hiranaka et al, 2013) and could suggest the occurrence of critical valence Error bars have been estimated as 5× the statistical error provided by the Rietveld refinement and are smaller than the data symbol size. Adapted from (Eloirdi et al, 2017).…”

Section: B High Intensity and Resolutionmentioning

confidence: 99%

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Synchrotron Radiation Techniques and their Application to Actinide Materials

Caciuffo¹,

Lander²,

Laan³

2022

Preprint

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Research on actinide materials, both basic and applied, has been greatly advanced by the general techniques available from high-intensity photon beams from x-ray synchrotron sources. The most important single reason is that such x-ray sources can work with minute (e.g., microgram) samples, and at this level the radioactive hazards of actinides are much reduced. We start by discussing the form and encapsulation procedures used for different techniques, then discuss the basic theory for interpreting the results. By reviewing a selection of x-ray diffraction (XRD), resonant elastic x-ray scattering (REXS), x-ray magnetic circular dichroism (XMCD), resonant and non-resonant inelastic scattering (RIXS, NIXS), dispersive inelastic x-ray scattering (IXS), and conventional and resonant photoemission experiments, we demonstrate the potential of synchrotron radiation techniques in studying lattice and electronic structure, hybridization effects, multipolar order, and lattice dynamics in actinide materials. CONTENTS I. Introduction 1 II. Samples and beamlines 3 References 49

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Section: B High Intensity and Resolutionmentioning

confidence: 99%

Section: B High Intensity and Resolutionmentioning

confidence: 99%

Synchrotron Radiation Techniques and their Application to Actinide Materials

Caciuffo¹,

Lander²,

Laan³

2022

Preprint

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“…On the other hand, the relaxation rate isotope ratio T −1 1 ( 71 Ga)/T −1 1 ( 69 Ga) provided by Nuclear Quadrupole Resonance is not compatible with the presence of charge fluctuations in the normal state, but rather indicates the presence of anisotropic SFs [15] that could, nevertheless, be associated with charge (valence) fluctuations with a higher energy scale. High-resolution powder x-ray-diffraction recently showed that the volume expansion of PuCoGa 5 deviates from the curve expected for a simple Grüneisen-Einstein model, but the observed variations are too small to be taken as an indication for the proximity of the system to a valence instability [16]. The origin of SC in PuCoGa 5 remains therefore unclear.…”

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confidence: 97%

Probing Magnetism in the Vortex Phase of PuCoGa5 by X-Ray Magnetic Circular Dichroism

et al. 2017

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We have measured X-ray magnetic circular dichroism (XMCD) spectra at the Pu M4,5 absorption edges from a newly-prepared high-quality single crystal of the heavy fermion superconductor 242 PuCoGa5, exhibiting a critical temperature Tc = 18.7 K. The experiment probes the vortex phase below Tc and shows that an external magnetic field induces a Pu 5f magnetic moment at 2 K equal to the temperature-independent moment measured in the normal phase up to 300 K by a SQUID device. This observation is in agreement with theoretical models claiming that the Pu atoms in PuCoGa5 have a nonmagnetic singlet ground state resulting from the hybridization of the conduction electrons with the intermediate-valence 5f electronic shell. Unexpectedly, XMCD spectra show that the orbital component of the 5f magnetic moment increases significantly between 30 and 2 K; the antiparallel spin component increases as well, leaving the total moment practically constant. We suggest that this indicates a low-temperature breakdown of the complete Kondo-like screening of the local 5f moment.PuCoGa 5 is a prototypical heavy-fermion compound that becomes a superconductor below T c ≃ 18.5 K [1], the highest critical temperature of any heavy-fermion material. Fifteen years on its discovery, the nature of the pairing boson in PuCoGa 5 remains an open question. Superconductivity (SC) mediated by spin fluctuations (SFs) associated with the proximity to an antiferromagnetic (AFM) quantum critical point (QCP) was initially proposed. The hypothesis was supported by the observation in the normal phase of a Curie-Weiss (CW) behavior of the magnetic susceptibility χ m , suggesting the presence of Pu atoms carrying a local magnetic moment. Further arguments in favor of SFs-controlled SC were provided by NMR studies [2], revealing a nodal-gap function separating the condensate from the unpaired states. Subsequent point-contact spectroscopy measurements confirmed that the wavefunction of the paired electrons has an unconventional d-wave symmetry [3]. However, the SF conjecture was questioned [4,5] after polarized neutron diffraction failed to observe a local magnetic moment in the normal state of PuCoGa 5 [6], pointing to an extrinsic origin of the reported temperature dependent χ m . This observation is confirmed in the present article by showing that the magnetic susceptibility of an almost defect-free PuCoGa 5 single crystal is weak and temperature-independent from T c up to room temperature.Other members of the PuM X 5 family (M = Co, Rh, and X = Ga, In) also become superconductors, with T c ranging from ∼1.7 K in the case of PuRhIn 5 to ∼8.7 K for PuRhGa 5 [7]. The much larger T c of PuCoGa 5 could indicate that a different pairing mechanism is acting in the various compounds of the family. Indeed, Bauer et al.[8] proposed that SC in PuCoIn 5 (T c = 2.5 K) is related to an AFM QCP, whereas PuCoGa 5 would reside on a larger SC dome in the temperature-pressure (hybridization strength) phase diagram, around a valence fluctuation (VF) QCP. The hypothesis is suppor...

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“…As an example of high resolution XRD study, we show in Fig. 3 the results obtained for the PuCoGa 5 unconventional superconductor (Eloirdi et al, 2017). The experiment was performed at the ESRF ID22 beamline, affording a resolution Ád/d = 10 À6 at = 0.354155 A ˚.…”

Section: Figurementioning

confidence: 99%

X-ray synchrotron radiation studies of actinide materials

Caciuffo¹,

Lander²

2021

J Synchrotron Rad

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By reviewing a selection of X-ray diffraction (XRD), resonant X-ray scattering (RXS), X-ray magnetic circular dichroism (XMCD), resonant and non-resonant inelastic scattering (RIXS, NIXS), and dispersive inelastic scattering (IXS) experiments, the potential of synchrotron radiation techniques in studying lattice and electronic structure, hybridization effects, multipolar order and lattice dynamics in actinide materials is demonstrated.

show abstract

Thermal expansion of the heavy-fermion superconductor PuCoGa5

Cited by 10 publications

References 26 publications

Synchrotron Radiation Techniques and their Application to Actinide Materials

Synchrotron Radiation Techniques and their Application to Actinide Materials

Probing Magnetism in the Vortex Phase of PuCoGa5 by X-Ray Magnetic Circular Dichroism

X-ray synchrotron radiation studies of actinide materials

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