Fermi Surface Property and Characteristic Crystalline Electric Field Effect in PrIr<sub>2</sub>Zn<sub>20</sub>

Matsushita, Masaki; Sakaguchi, Jyunya; Taga, Yuki; Ohya, Masahiro; Yoshiuchi, Shingo; Ota, Hisashi; Hirose, Yusuke; Enoki, Kaori; Honda, Fuminori; Sugiyama, Kiyohiro; Hagiwara, Masayuki; Kindo, Koichi; Tanaka, Toshiki; Kubo, Yasunori; Takeuchi, Tetsuya; Settai, Rikio; Ōnuki, Yoshichika

doi:10.1143/jpsj.80.074605

Cited by 25 publications

(20 citation statements)

References 26 publications

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“…3 energy is approximately below 100 K, and this is consistent with the results of high-field magnetization. It is noted that the splitting energy is estimated to be 106 K in YbIr 2 Zn 20 [4] and 103 K in PrIr 2 Zn 20 [5].…”

Section: Experimental Results and Analysesmentioning

confidence: 99%

Magnetic Properties of RIr₂Zn₂₀(R: Rare Earth) with the Caged Structure

et al. 2012

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Section: Experimental Results and Analysesmentioning

confidence: 99%

Magnetic Properties of RIr₂Zn₂₀(R: Rare Earth) with the Caged Structure

et al. 2012

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“…The entropy released at T Q is only 0.2R ln 2, indicating that quadrupolar fluctuations could play an important role in the formation of Cooper pairs [382]. However, extremely low upper critical field values with upper limit H c2 (0) < 20 Oe are observed and cyclotron effective masses of order m 0 are obtained in quantum oscillation measurements [384], indicating that Cooper pairs are not formed from heavy quasiparticles in PrIr 2 Zn 20 . Though it is probably not a heavy-fermion compound, uncovering superconductivity in PrIr 2 Zn 20 (and in the related compound PrRh 2 Zn 20 at T c 0.06 K [385]) set the stage for the discovery of heavy-fermion superconductivity in other Pr-based 1-2-20 compounds with Γ 3 ground states.…”

Section: Superconductivity In Prt 2 X 20 Compoundsmentioning

confidence: 95%

Unconventional superconductivity in heavy-fermion compounds

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Thompson

Maple

2015

Physica C: Superconductivity and its Applications

126

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Over the past 35 years, research on unconventional superconductivity in heavy-fermion systems has evolved from the surprising observations of unprecedented superconducting properties in compounds that convention dictated should not superconduct at all to performing explorations of rich phase spaces in which the delicate interplay between competing ground states appears to support emergent superconducting states. In this article, we review the current understanding of superconductivity in heavy-fermion compounds and identify a set of characteristics that is common to their unconventional superconducting states. These core properties are compared with those of other classes of unconventional superconductors such as the cuprates and iron-based superconductors. We conclude by speculating on the prospects for future research in this field and how new advances might contribute towards resolving the long-standing mystery of how unconventional superconductivity works.

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“…7,8) In PrIr 2 Zn 20 , the SC emerges at 50 mK in the antiferroquadrupolar phase whose ordering temperature is T Q ¼ 0:11 K. The critical field has not been precisely determined, but is known to be <20 Oe. 35) In contrast with the strong hybridization effects in PrTi 2 Al 20 , 4f electrons are so localized in PrIr 2 Zn 20 that do not exhibit the Kondo effect in ðT Þ, show nearly Curie behavior of ðT Þ with a vanishingly small Â W , and have the cyclotron effective mass of m Ã cyc =m 0 $ 1. 8,35) Thus, the origin of the higher T c of the superconductivity in PrTi 2 Al 20 than in PrIr 2 Zn 20 may partly come from the larger effective mass or density of states of itinerant electrons coming from the stronger hybridization.…”

Section: à6mentioning

confidence: 99%

“…35) In contrast with the strong hybridization effects in PrTi 2 Al 20 , 4f electrons are so localized in PrIr 2 Zn 20 that do not exhibit the Kondo effect in ðT Þ, show nearly Curie behavior of ðT Þ with a vanishingly small Â W , and have the cyclotron effective mass of m Ã cyc =m 0 $ 1. 8,35) Thus, the origin of the higher T c of the superconductivity in PrTi 2 Al 20 than in PrIr 2 Zn 20 may partly come from the larger effective mass or density of states of itinerant electrons coming from the stronger hybridization. In this case, the superconducting T c and its associated effective mass would increase under pressure as pressure enhances the hybridization and suppresses the quadrupolar ordering temperature.…”

Section: à6mentioning

confidence: 99%

Superconductivity in the Ferroquadrupolar State in the Quadrupolar Kondo Lattice PrTi₂Al₂₀

2012

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The cubic compound PrTi 2 Al 20 is a quadrupolar Kondo lattice system that exhibits quadrupolar ordering due to the non-Kramers À 3 ground doublet and has strong hybridization between 4f and conduction electrons. Our study using high-purity single crystals reveals that PrTi 2 Al 20 exhibits type-II superconductivity at T c ¼ 200 mK in the nonmagnetic ferroquadrupolar state. The superconducting critical temperature and field phase diagram indicates clean limit superconductivity with moderately enhanced effective mass of m Ã =m 0 $ 16. Orbital degree of freedom in strongly correlated electron systems leads to rich variety of nontrivial phenomena, such as colossal magnetoresistance, orbital ordering, 1) and spinorbital disordered states.2) In particular, for the study of topical subjects of d-electron systems including hightemperature superconductivity and frustrated magnetism, orbital arrangement has been found to provide an important basis to understand the underlying electronic and spin structures. This is because of the strong coupling between orbital, spin and charge degrees of freedom, which, on the other hand, makes it hard to study purely orbital-driven effects.Interestingly, however, f -electron systems may provide a rare example of nonmagnetic ground states that have mainly orbital degree of freedom known as quadrupolar moments, i.e., irreducible tensor operators of the total angular momentum J.3) In particular, cubic Pr and U based compounds with 4f 2 configuration are known to sometimes exhibit a nonmagnetic ground state with the À 3 quadrupolar degree of freedom. In comparison with the uranium compounds, Pr based materials have been found to exhibit rich variety of electronic ground state due to quadrupole moments, such as ferro-and antiferroquadrupolar states, e.g., in PrPtBi and PrPb 3 , [4][5][6] and superconductivity in a quadrupolar phase in PrIr 2 Zn 20 . 7,8) Moreover, for these nonmagnetic states, the hybridization between the 4f and conduction electrons is expected to lead to two competing interactions. One is the indirect RKKY type intersite coupling between quadrupole moments, which may sometimes induce incommensurate modulated structure as observed in PrPb 3 .6) The other is the two-channel (quadrupolar) Kondo effect that quenches the orbital degrees of freedom and stabilize an anomalous metallic state. [9][10][11] For Ce and Yb based compounds described as Kondo lattice systems, it is known that the competition between the Kondo effect and RKKY interaction gives rise to quantum criticality and related phenomena such as unconventional superconductivity and non-Fermi liquid behavior. In analogy, novel quantum criticality and exotic superconductivity might arise as a result of the competition between the quadrupolar Kondo effect and RKKY interaction.In the search for the novel screening effects, pioneer works on the cubic 4f 2 À 3 systems PrInAg 2 and PrMg 3 have found that these compounds do not exhibit any long-range order 12,13) and suggested a nonmagnetic heavy fermion state due to the qu...

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Fermi Surface Property and Characteristic Crystalline Electric Field Effect in PrIr₂Zn₂₀

Cited by 25 publications

References 26 publications

Magnetic Properties of RIr₂Zn₂₀(R: Rare Earth) with the Caged Structure

Magnetic Properties of RIr₂Zn₂₀(R: Rare Earth) with the Caged Structure

Unconventional superconductivity in heavy-fermion compounds

Superconductivity in the Ferroquadrupolar State in the Quadrupolar Kondo Lattice PrTi₂Al₂₀

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Fermi Surface Property and Characteristic Crystalline Electric Field Effect in PrIr2Zn20

Cited by 25 publications

References 26 publications

Magnetic Properties of RIr2Zn20(R: Rare Earth) with the Caged Structure

Magnetic Properties of RIr2Zn20(R: Rare Earth) with the Caged Structure

Unconventional superconductivity in heavy-fermion compounds

Superconductivity in the Ferroquadrupolar State in the Quadrupolar Kondo Lattice PrTi2Al20

Contact Info

Product

Resources

About

Fermi Surface Property and Characteristic Crystalline Electric Field Effect in PrIr₂Zn₂₀

Magnetic Properties of RIr₂Zn₂₀(R: Rare Earth) with the Caged Structure

Magnetic Properties of RIr₂Zn₂₀(R: Rare Earth) with the Caged Structure

Superconductivity in the Ferroquadrupolar State in the Quadrupolar Kondo Lattice PrTi₂Al₂₀