Possibility of Valence-Fluctuatsion-Mediated Superconductivity in Cd-Doped<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>CeIrIn</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:math>Probed by In NQR

Yashima, M.; Tagami, N.; Taniguchi, Satoshi; Uematsu, K.; Mukuda, H.; Kitaoka, Y.; Ota, Yoshiyuki; Honda, Fuminori; Settai, Rikio; Ōnuki, Yoshichika

doi:10.1103/physrevlett.109.117001

Cited by 20 publications

(29 citation statements)

References 27 publications

(50 reference statements)

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“…Our results provide solid evidence that CeIrIn 5 is located near an AFM instability rather than a valence instability and the SC of CeIrIn 5 is associated with critical spin fluctuations, being similar to many other HF superconductors. We note that the strongest evidence for scenario II in CeIrIn 5 is due to the increase of T sc in the pure compound under pressure [17,18]. However, a similar increase of T sc under pressure is observed in pure CeCoIn 5 where spin-fluctuation mediated SC is generally believed [8].…”

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confidence: 54%

“…CeIrIn 5 was argued to exist far from an AFM QCP and be located at a cusp-like minimum of T sc which bridges the two superconducting domes [16]. Accordingly, superconductivity of CeIrIn 5 was proposed to be mediated by valence fluctuations rather than by spin fluctuations [16][17][18], which are more commonly taken to mediate pairing in HF superconductors (Scenario I in Fig. 1) [13,19].…”

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confidence: 99%

“…1) [13,19]. However, no solid evidence of a valence instability has been revealed in CeIrIn 5 , even though nuclear quadrupolar resonance (NQR) experiments detected some differences between the two superconducting domes [17,18]. On the other hand, analyses of nuclear spin-lattice re- [11], which applies to most Ce-based HF superconductors including CeCoIn5 and CeRhIn5 [4][5][6][7][8].…”

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CeIrIn5: Superconductivity on a magnetic instability

et al. 2014

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We report the doping-induced antiferromagnetic state and Fermi liquid state that are connected by a superconducting region in a series of CeIrIn5−xHgx, CeIrIn5−xSnx and CeIr1−xPtxIn5 single crystals. Measurements of the specific heat C(T ) and electrical resistivity ρ(T ) demonstrate that hole doping via Hg/In substitution gives rise to an antiferromagnetic ground state, but substitutions of In by Sn or Ir by Pt (electron doping) favor a paramagnetic Fermi liquid state. A cone-like non-Fermi liquid region is observed near CeIrIn5, showing a diverging effective mass on the slightly Hg-doped side. The obtained temperature-doping phase diagram suggests that CeIrIn5 is in proximity to an antiferromagnetic quantum critical point, and heavy fermion superconductivity in this compound is mediated by magnetic quantum fluctuations rather than by valence fluctuations.

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CeIrIn5: Superconductivity on a magnetic instability

et al. 2014

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“…Because there is no evidence for PuCoGa 5 being in proximity to a magnetically ordered state (10), it is unlikely that magnetic fluctuations are the primary driver of its anomalously high T c of 18.5 K (11). Valence fluctuationswhere the total number of f electrons per ion fluctuates with the conduction band or the configuration of a fixed number of f electrons fluctuates between two or more nearly degenerate f states (sometimes known as orbital fluctuations)-have been proposed as a possible alternative mechanism for superconductivity in several heavy-fermion systems (12)(13)(14)(15). Here, we report that PuCoGa 5 's elastic moduli soften over a large temperature range above T c .…”

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confidence: 79%

Avoided valence transition in a plutonium superconductor

Ramshaw

Shekhter

McDonald

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The d and f electrons in correlated metals are often neither fully localized around their host nuclei nor fully itinerant. This localized/ itinerant duality underlies the correlated electronic states of the high-T c cuprate superconductors and the heavy-fermion intermetallics and is nowhere more apparent than in the 5f valence electrons of plutonium. Here, we report the full set of symmetryresolved elastic moduli of PuCoGa 5 -the highest T c superconductor of the heavy fermions (T c = 18.5 K)-and find that the bulk modulus softens anomalously over a wide range in temperature above T c . The elastic symmetry channel in which this softening occurs is characteristic of a valence instability-therefore, we identify the elastic softening with fluctuations of the plutonium 5f mixed-valence state. These valence fluctuations disappear when the superconducting gap opens at T c , suggesting that electrons near the Fermi surface play an essential role in the mixed-valence physics of this system and that PuCoGa 5 avoids a valence transition by entering the superconducting state. The lack of magnetism in PuCoGa 5 has made it difficult to reconcile with most other heavy-fermion superconductors, where superconductivity is generally believed to be mediated by magnetic fluctuations. Our observations suggest that valence fluctuations play a critical role in the unusually high T c of PuCoGa 5 .unconventional superconductivity | heavy fermions | quantum criticality | valence fluctuations | resonant ultrasound spectroscopy P uCoGa 5 enters the superconducting state below T c = 18:5 K (1)-an order of magnitude higher than all Ce-or U-based superconductors. This contrast raises the question of whether PuCoGa 5 simply benefits from a higher superconducting-pairing energy scale than its U-and Ce-based relatives or instead, whether PuCoGa 5 is host to a completely different pairing mechanism. In many lanthanide and actinide compounds, the f electrons are nearly degenerate with the conduction band. In addition, the outer f-shell states are close in energy and may support two (or more) nearly degenerate valence configurations (2). In some cases, this valence degeneracy becomes unstable, leading to valence fluctuations and ultimately, a transition to a different valence state as a function of temperature, pressure, and/or doping (3). X-ray and photoemission spectroscopy (4, 5), neutron form factor measurements (6), and theoretical calculations (7) all indicate that PuCoGa 5 is in an intermediate valence state, with the 5f 6 (Pu 2+

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“…Thus the origin of the SC of CeIrIn5 is expected to be the non-magnetic fluctuation. Nuclear quadrupole resonance (NQR) measurement of Cd doped CeIrIn5 suggests a valence instability contributes to the SC2 [10]. On the other hands, nuclear magnetic resonance (NMR) and transport measurements suggest CeIrIn5 is in the vicinity of AFM QCP [11][12][13][14][15].…”

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confidence: 99%

Physical properties of Cd doped CeIrIn₅ under pressure

Tsunoda¹,

Hirose²,

Settai³

2017

Proc. 17th Int. Conf. On High Pressure in Semiconductor Physics &Amp; Workshop on High-Pressure Study on Superconducting

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We measured the electrical resistivity ρ of CeIr(In1-xCdx)5 under pressure for x = 0.05 and 0.10, which show the onset of superconductivity (SC) at Tsc onset ~ 0.9 K and antiferromagnetic transition at TN ~ 3.4 K. For x = 0.05, Tsc onset increases by applying pressure up to 2.8 GPa and zero resistivity is observed at Tsc ρ=0 above 2.4 GPa. For x = 0.10, the pressure dependence of TN shows peak at around 2 GPa and TN seems to be 0 K toward 3 GPa, where SC phase appears. The maximum value of Tsc ρ=0 is independent on amount of doped Cd, showing 1.35 K. We analyzed the temperature dependence of the electrical resistivity ρ for x = 0.05 and 0.10 under pressure using the following equation, ρ = ρ0 + AT n . This analysis revealed that ρ shows the sublinear temperature dependence (n < 1) in the wide temperature region above Tsc ρ=0 , and ρ0 decreases abruptly in the pressure region where Tsc ρ=0 indicates a maximum.

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Possibility of Valence-Fluctuatsion-Mediated Superconductivity in Cd-DopedCeIrIn5Probed by In NQR

Cited by 20 publications

References 27 publications

CeIrIn5: Superconductivity on a magnetic instability

CeIrIn5: Superconductivity on a magnetic instability

Avoided valence transition in a plutonium superconductor

Physical properties of Cd doped CeIrIn₅ under pressure

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Possibility of Valence-Fluctuatsion-Mediated Superconductivity in Cd-DopedCeIrIn5Probed by In NQR

Cited by 20 publications

References 27 publications

CeIrIn5: Superconductivity on a magnetic instability

CeIrIn5: Superconductivity on a magnetic instability

Avoided valence transition in a plutonium superconductor

Physical properties of Cd doped CeIrIn5 under pressure

Contact Info

Product

Resources

About

Physical properties of Cd doped CeIrIn₅ under pressure