Pressure-induced metal-insulator transition in the filled skutterudite<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:mi>Pr</mml:mi><mml:msub><mml:mrow><mml:mi mathvariant="normal">Fe</mml:mi></mml:mrow><mml:mn>4</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">P</mml:mi><mml:mrow><mml:mn>12</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:mrow></mml:math>

Hidaka, Hisao; Ando, Ikuma; Kotegawa, Hisashi; Kobayashi, Tatsuo; Harima, Hisatomo; Kobayashi, Miki; Sugawara, Hitoshi; Sato, Hideyuki

doi:10.1103/physrevb.71.073102

Cited by 41 publications

(24 citation statements)

References 23 publications

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“…A study of electrical resistivity under hydrostatic pressure 36) revealed a MI transition at about 2.4 GPa. The resistivity with increasing pressure is shown in Fig.…”

Section: )mentioning

confidence: 99%

Multipole Orders and Fluctuations in Strongly Correlated Electron Systems

2009

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In this paper we review experimental and theoretical results on higher electronic multipoles in solids with strong correlations. Recent experiments and their theoretical interpretation have confirmed the ordering of octupoles and even higher multipoles in rare-earth and actinide compounds with f electrons. The concept of multipoles is critically examined in point groups where spherical tensors of different ranks mix. Using a phenomenological approach, we demonstrate how linear and nonlinear couplings of different multipoles lead to rich phase diagrams and anomalies in physical observables. As actual representative systems, we first consider Ce x La 1Àx B 6 , for which resonant X-ray scattering probed the octupole order for the first time, and NpO 2 , where quadrupoles induced by the octupole order have been observed. We then consider a class of compounds called skutterudites as the most convenient system for systematic study. Particular emphasis is placed on the ordering of scalar components from fourth-rank tensors (hexadecapoles) and sixth-rank tensors (hexacontatetrapoles). A comparison of a skutterudite PrFe 4 P 12 and URu 2 Si 2 is made, where much fewer carriers remain in the ordered states than in the disordered phase. The even number (two) of f electrons per site in Pr 3þ or U 4þ makes the system free from the Kramers degeneracy, in contrast to standard models for Mott transitions. Hence, it is pointed out that multipole orders, particularly the scalar order, should provide a new route for studying the dichotomy between the itinerant and localized behaviors of electrons.

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“…A study of electrical resistivity under hydrostatic pressure 36) revealed a MI transition at about 2.4 GPa. The resistivity with increasing pressure is shown in Fig.…”

Section: )mentioning

confidence: 99%

Multipole Orders and Fluctuations in Strongly Correlated Electron Systems

2009

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“…Using the result obtained for the hyperfine constants shown in Table I, we can find in the expression (21) that both the linear (h(k) 1 ) and third-order (h(k) 3 ) terms of the homogenous shift are dominated by the components of the uniform magnetization. Therefore, the ratio of the third-order and linear terms of the homogenous shift is estimated as h(k) 3 /h(k) 1 ≈ (M 13 + M 33 )/M 11 ≈ 0.02.…”

Section: Fitting Of the Nmr Splitting Pattern For H||(111) And H||(110)mentioning

confidence: 99%

“…Among them PrFe 4 P 12 has mysterious ordered phases, 1, 2 metal-insulator transition and magnetic transition under high pressure. 3 PrFe 4 P 12 undergoes a phase transition at T 0 = 6.5K, which is accompanied by a sharp peak in the magnetic susceptibility.…”

Section: Introductionmentioning

confidence: 99%

Consequence of Spatial Symmetry on³¹P NMR Spectra in PrFe₄P₁₂with Scalar Order

Kiss

Kuramoto

2008

J. Phys. Soc. Jpn.

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NMR (nuclear magnetic resonance) splitting pattern of 31 P is discussed for PrFe 4 P 12 assuming scalar order with Γ 1g symmetry. We extend our previous study of NMR spectra into the non-linear range of the external magnetic field, and discuss magnetic anisotropy. A background is provided of the phenomenological formula for the NMR splitting pattern. It is shown that the field dependence of the NMR splitting can be reproduced for the field directions (001), (111) and (110) with account of the measured Pr magnetization. The hyperfine constants for the dipolar field coming from the Pr dipole moment are calculated within classical approximation, and the transferred hyperfine constants are deduced from the fitting of the NMR splitting pattern.

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“…Pr-based filled skutterudite is one of the most interesting series among them. At ambient pressure, PrFe 4 P 12 shows the dense Kondo behavior at high temperature and the multipole order state at low temperature, and PrRu 4 P 12 shows metal-insulator transition at 60 K. [1][2][3][4] Once under pressures, PrFe 4 P 12 undergoes the change from the metallic state with multipole order to the insulating state with antiferromagnetic order at low temperature, [5][6][7] and the metallic state with superconducting at 1.8 K is revived above 11 GPa in PrRu 4 P 12 .…”

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Pressure Effect on Pr-based Skutterudite Compounds

et al. 2008

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The pressure-induced metal-insulator transition in PrRu4P12 has been examined by the optical study at 20 K. The reflectivity and the optical conductivity clearly showed the change from an insulator to a metal across 8 GPa. The temperature-induced gap was stabilized by pressure in the realm of insulating state below 8 GPa. The typical metallic spectra with a finite Drude component were observed in both reflectivity and optical conductivity above 8 GPa.KEYWORDS: metal-insulator transition, high pressure, infrared microscope, skutterudite Filled-skutterudite RT 4 X 12 (R=rare earth metals; T=Fe, Ru, Os; X=P, As, Sb) have been known to have interesting physical properties such as superconductivity, thermoelectric effect, heavy Fermion behavior, metalinsulator transition. Pr-based filled skutterudite is one of the most interesting series among them. At ambient pressure, PrFe 4 P 12 shows the dense Kondo behavior at high temperature and the multipole order state at low temperature, and PrRu 4 P 12 shows metal-insulator transition at 60 K.1-4 Once under pressures, PrFe 4 P 12 undergoes the change from the metallic state with multipole order to the insulating state with antiferromagnetic order at low temperature, 5-7 and the metallic state with superconducting at 1.8 K is revived above 11 GPa in PrRu 4 P 12 .9, 10 The perfection of the nesting in Fermi surface and the strong c-f hybridization play important roles for the complex metal-insulator changes in PrFe 4 P 12 and PrRu 4 P 12 . 11, 12In this study, we carried out the optical measurements under pressure at low temperature for PrRu 4 P 12 . The measurements were performed using an infrared spectromicroscope at BL43IR in SPring-8 and our laboratory. High pressures were induced using a diamond anvil cell (DAC) with a type II-a diamond having culet in diameter of 0.6 mm. The pressures were determined by the ruby fluorescence technique.13 The single crystal sample with mirror surface and several ruby tips were settled on the diamond surface and were sealed into a stainless steel gasket with an oil-based pressure medium. The reliable reflectivity for the sample in DAC was derived from the multistep analytical procedure using an Au foil as a tentative reference.14 The high pressure was applied up to 14 GPa using a membrane-type pressure generating apparatus. The low temperature of 20 K was achieved using a liquid He flow-type Oxford cryostat with a thermal radiation shield. Figure 1 shows the pressure change of optical reflectivity R(ω) in far-infrared (FIR) region for PrRu 4 P 12 at 20 K. Applying pressure, the reflectivity declines consecutively up to 8 GPa, and its photon energy dependence suddenly changes above 8 GPa. The gradient of reflectivity versus photon energy turns to be upward toward 1 at ω = 0. The insulating state at ambient pressure with poor photon energy dependence should change to be metallic state under pressure. Figure 2 shows the pressure change of optical conductivity σ(ω) obtained from the Kramers-Kronig transformation of reflectivity R(ω) at 20 K...

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Pressure-induced metal-insulator transition in the filled skutteruditePrFe4P12

Cited by 41 publications

References 23 publications

Multipole Orders and Fluctuations in Strongly Correlated Electron Systems

Multipole Orders and Fluctuations in Strongly Correlated Electron Systems

Consequence of Spatial Symmetry on³¹P NMR Spectra in PrFe₄P₁₂with Scalar Order

Pressure Effect on Pr-based Skutterudite Compounds

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Pressure-induced metal-insulator transition in the filled skutteruditePrFe4P12

Cited by 41 publications

References 23 publications

Multipole Orders and Fluctuations in Strongly Correlated Electron Systems

Multipole Orders and Fluctuations in Strongly Correlated Electron Systems

Consequence of Spatial Symmetry on31P NMR Spectra in PrFe4P12with Scalar Order

Pressure Effect on Pr-based Skutterudite Compounds

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Consequence of Spatial Symmetry on³¹P NMR Spectra in PrFe₄P₁₂with Scalar Order