Observation of Modulated Quadrupolar Structures in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>PrPb</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Onimaru, Takahiro; Sakakibara, Toshiro; Aso, Naofumi; Yoshizawa, H.; Suzuki, Hiroyuki; Takeuchi, Tetsuya

doi:10.1103/physrevlett.94.197201

Cited by 130 publications

(93 citation statements)

References 31 publications

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“…Such a nonmagnetic ground state is known as the Γ 3 doublet in the cubic crystalline electric field (CEF) of a f 2 configuration. Intensive studies have revealed various interesting states in the cubic Γ 3 doublet systems, in particular in Pr-based intermetallic compounds [8][9][10][11][12]. However, Pr-based cubic Γ 3 doublet systems usually have well-localized quadrupole moments, and thus until quite recently there have been no study on the quadrupolar instability by tuning the c-f hybridization.…”

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confidence: 99%

Heavy-Fermion Superconductivity in the Quadrupole Ordered State ofPrV2Al20

et al. 2014

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PrV2Al20 is a rare example of a heavy fermion system based on strong hybridization between conduction electrons and nonmagnetic quadrupolar moments of the cubic Γ3 ground doublet. Here, we report that a high-quality single crystal of PrV2Al20 exhibits superconductivity at Tc = 50 mK in the antiferroquadrupole-ordered state under ambient pressure. The heavy fermion character of the superconductivity is evident from the specific heat jump of ∆C/T ∼ 0.3 J/mol K 2 and the effective mass m * /m0 ∼ 140 estimated from the temperature dependence of the upper critical field. Furthermore, the high-quality single crystals exhibit double transitions at TQ = 0.75 K and T * = 0.65 K associated with quadrupole and octapole degrees of freedom of the Γ3 doublet. In the ordered state, the specific heat C/T shows a T 3 dependence, indicating the gapless mode associated with the quadrupole and/or octapole order. The strong sensitivity to impurity of the superconductivity suggests unconventional character due to significant quadrupolar fluctuations.PACS numbers: 74.70. Tx, 75.25.Dk, 72.15.Qm 4f electron systems exhibit a large variety of nontrivial ground states by tuning the hybridization between localized 4f and conduction (c−) electrons. Especially, emergence of exotic superconductivity (SC) with a large effective mass from unconventional quantum criticality has attracted much attention [1][2][3][4][5]. While most of the examples have been reported at the border of magnetism [6,7], similarly exotic states of matter may be found in the vicinity of quantum phase transition associated with different degrees of freedom of f -electrons, such as electrical quadrupole (orbital) and valence. In particular, experimental exploration of the quadrupolar instability is important since few studies on the associated quantum criticality has been made to date.For the exploration, the simplest example could be found in materials that carry no magnetic but quadrupole moments. Such a nonmagnetic ground state is known as the Γ 3 doublet in the cubic crystalline electric field (CEF) of a f 2 configuration. Intensive studies have revealed various interesting states in the cubic Γ 3 doublet systems, in particular in Pr-based intermetallic compounds [8][9][10][11][12]. However, Pr-based cubic Γ 3 doublet systems usually have well-localized quadrupole moments, and thus until quite recently there have been no study on the quadrupolar instability by tuning the c-f hybridization.PrT r 2 Al 20 (T r = Ti, V) has been reported as a rare example of cubic Γ 3 -doublet based Kondo lattice systems where one may tune the hybridization strength between quadrupole moments and conduction electrons by chemical substitution and by pressure [13,14]. These materials have the nonmagnetic Γ 3 CEF ground state with the well separated excited state at ∆ CEF ∼ 60 K (Ti) and 40 K (V), as confirmed by various experiments [13,15,16], and * Electronic address: satoru@issp.u-tokyo.ac.jp exhibit the respective ferro-and antiferro-quadrupole ordering at T Q = 2.0 K (Ti) and 0.6 K (...

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Heavy-Fermion Superconductivity in the Quadrupole Ordered State ofPrV2Al20

et al. 2014

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“…The additional new magnetic structures that develop below the primary ordering temperature have different temperature and field dependencies than the quadrupolar order observed in PrPb 3 and therefore appear to have a different origin. 18 A quadrupolar order generally results from the degenerate orbital level which carries a quadrupolar moment. These small moments are strongly field-dependent and become stronger as the applied field is increased, which is opposite to what we observe.…”

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Multiple magnetic structures of correlated Ce ions in intermetallic CeAu2Ge2

et al. 2012

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Neutron diffraction measurements on a high quality single crystal of CeAu2Ge2 reveal two new magnetic structures that coexist with commensurate long range antiferromagnetic order below the Neel temperature TN 14 K. The new magnetic structures, which exhibit distinct temperature and field dependencies, are described by both commensurate and incommensurate magnetic structures and introduces new region in the H-T phase diagram. These new experimental observations provide essential information for developing a universal understanding of the magnetic properties of this class of Ce-based CeX2M 2 (X = Cu, Ag, Au; M = Ge, Si) compounds, which are prototypes for exploring quantum phase transitions and their interplay with unconventional superconductivity.

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“…1 Nonlinear susceptibility measurements disfavored such scenario, 7 however, and indicated instead the possibility of a mixedvalence state. 8 The latter was also supported by de Haasvan Alphen measurements of uranium-doped samples of ThBe 13 . 9 The new scenario necessitates the study of the full two-channel Anderson model away from its localmoment regimes, where a low-energy Kondo-Hamiltonian description is not available.…”

Section: Introductionmentioning

confidence: 72%

“…4 The situation is similar in the case of praseodymium compounds. 5,6 For the case of UBe 13 , it was originally speculated that the Γ 3 doublet would constitute the lowest-energy ionic configuration. This opened the possibility of a quadrupolar route to two-channel Kondo physics, in which a local quadrupolar moment would be screened by conduction electrons whose spin degree of freedom would provide the two degenerate channels.…”

Section: Introductionmentioning

confidence: 99%

Bosonization approach to the mixed-valence two-channel Kondo problem

Iucci

Bolech

2008

Phys. Rev. B

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We present in detail the bosonization-refermionization solution of the anisotropic version of the two-channel Anderson model at a particular manifold in the space of parameters of the theory, where we establish an equivalence with a Fermi-Majorana biresonant-level model. The correspondence is rigorously proved by explicitly constructing the new fermionic fields and Klein factors in terms of the original ones and showing that the commutation properties between original and new Klein factors are of semionic type. We also demonstrate that the fixed points associated with the solvable manifold are renormalization-group stable and generic, and therefore representative of the physics of the original model. The simplicity of the solution found allows for the computation of the full set of thermodynamic quantities. In particular, we compute the entropy, occupation, and magnetization of the impurity as functions of temperature, and identify the different physical energy scales. In the absence of external fields, two energy scales appear and, as the temperature goes to zero, a nontrivial residual entropy indicates that the model approaches a universal line of fixed points of non-Fermi-liquid type. An external field, even if small, introduces a third energy scale and causes the quenching of the impurity entropy to zero, taking the system to a corresponding Fermi-liquid fixed point.

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Observation of Modulated Quadrupolar Structures inPrPb3

Cited by 130 publications

References 31 publications

Heavy-Fermion Superconductivity in the Quadrupole Ordered State ofPrV2Al20

Heavy-Fermion Superconductivity in the Quadrupole Ordered State ofPrV2Al20

Multiple magnetic structures of correlated Ce ions in intermetallic CeAu2Ge2

Bosonization approach to the mixed-valence two-channel Kondo problem

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