Evidence for Ferromagnetic Fluctuations in Filled Skutterudite LaFe<sub>4</sub>Sb<sub>12</sub>:Sb-NQR and La-NMR

Magishi, Ko−ichi; Nakai, Yusuke; Ishida, K.; Sugawara, Hitoshi; Mori, Ikuko; Saito, Takahito; Koyama, Kuniyuki

doi:10.1143/jpsj.75.023701

Cited by 26 publications

(31 citation statements)

References 19 publications

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“…Since K and 1/T 1 T probes χ 0 = χ(0, 0) and ∑ q χ(q, ω → 0), the enhancement of 1/T 1 T upon cooling indicates the development of antiferromagnetic correlations. Figure 5 displays the 121,123 Sb-NQR spectra at 4.2 K for two Sb isotopes of (a) La 0.5 Co 4 Sb 12 , together with those for (b) La 0.9 Fe 4 Sb 12 [7] and (c) LaFe 4 Sb 12 [8]. The observed five NQR lines consist of two transitions for 121 Sb (I = 5/2) and three transitions for 123 Sb (I = 7/2).…”

Section: Resultsmentioning

confidence: 99%

“…The magnitude of 1/T 1 T for La 0.5 Co 4 Sb 12 is larger than those for La 0.9 Fe 4 Sb 12 and LaFe 4 Sb 12 , suggesting that the magnetic fluctuations seem to be strong. In case of LaFe 4 Sb 12 , ferromagnetic fluctuations are suggested to develop upon cooling by the following relation 1/T 1 T ∝ χ 0 [7,8], as shown by dotted curve in the figure. On the other hand, for La 0.5 Co 4 Sb 12 , 1/T 1 T obeys the following temperature dependence 1/T 1 T = C/ √ (T + θ) with θ = 30 K indicated by solid curve, which is similar to the result of 59 Co-NMR as mentioned before.…”

Section: 123 Sb-nqrmentioning

confidence: 94%

“…In case of I = 5/2 and η = 0.43, the recovery curve for ±5/2 ↔ ±3/2 transition is given by [7] and LaFe 4 Sb 12 [8]. From the estimation of the T 1 ratio for two isotopes 121,123 Sb (not shown), the ratio 121 T 1 / 123 T 1 ∼ 0.3 is close to the ratio of the square of the nuclear gyromagnetic ratio ( 123 γ N / 121 γ N ) 2 ∼ 0.29, indicating that the T 1 process is dominated by magnetic fluctuations.…”

Section: 123 Sb-nqrmentioning

confidence: 99%

“…We also present the results of filled skutterudite LaFe 4 Sb 12 [7,8], in order to compare the influence of the La-site filling fraction and the substitution of Fe in place of Co on the magnetic properties. Spin-Echo Intensity (arb.…”

Section: Introductionmentioning

confidence: 99%

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NMR/NQR Study of Filled Skutterudite La_0.5Co₄Sb₁₂

Magishi

Kusaka

Hisada

et al. 2014

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)

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We report the results of the 59 Co-nuclear magnetic resonance (NMR) and 121,123 Sb-nuclear quadrupole resonance (NQR) measurements on partially filled skutterudite La 0.5 Co 4 Sb 12 synthesized under high pressure in order to understand the microscopic electronic states and the La substitution effect to CoSb 3 . The 59 Co-NMR spectrum is almost temperature-independent, indicating that the uniform susceptibility is independent of temperature. Also, the nuclear spin-lattice relaxation rates divided by temperature 1/T 1 T 's for both 59 Co and 121 Sb increase with decreasing temperature as 1/T 1 T = C/ √ (T + θ) with θ = 30 K, suggesting the development of the antiferromagnetic fluctuations upon cooling.

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Section: Resultsmentioning

confidence: 99%

Section: 123 Sb-nqrmentioning

confidence: 94%

Section: 123 Sb-nqrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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NMR/NQR Study of Filled Skutterudite La_0.5Co₄Sb₁₂

Magishi

Kusaka

Hisada

et al. 2014

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)

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“…3) was inferred to the critical slowing down of spin fluctuations associated with the ferromagnetic order. 3 Thus, we conjecture that with increasing the extent of Yb-deficiency, the itinerant 3d electrons of anion [Fe 4 Sb 12 ] begin to play an additional contribution to the weak ferromagnetism. Now we focus on the 1/T 2 and 1/T 1 maxima originating from the thermal motions of R ion in each Sbcage.…”

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confidence: 98%

Effect of Rare-Earth Filling Rate for the Physical Properties of Skutterudites Investigated through NMR/NQR Measurements

et al. 2008

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We have microscopically elucidated low-energy fluctuations in the completely filled skutterudites YbFe4Sb12 and LaFe4Sb12 through 121 Sb nuclear quadrupole resonance and 139 La nuclear magnetic resonance measurements. It provides evidence that upon cooling, YbFe4Sb12 transforms into a nonmagnetic heavy Fermi liquid state and LaFe4Sb12 remains the paramagnetic one, in contrast to the ferromagnetically ordered state and the heavy Fermi liquid-like one previously reported for the corresponding skutterudites with rare-earth deficiencies of about 10%. The local maxima in the longitudinal spin-lattice relaxation rate 1/T1 and transversal spin-spin relaxation rate 1/T2 for both LaFe4Sb12 and YbFe4Sb12 are ascribed to the freezing of thermal motions of rare-earth ion in each Sb-cage. It is suggested that the thermal motion of La ion (f 0 ) is of incoherent motion, whereas that of Yb ion (f 13 ) is of coherent one originating from possible interactions between f electrons in neighboring cages. It is also suggested that the coherent motion in YbFe4Sb12 is largely disturbed with increasing the extent of Yb-deficiency. KEYWORDS: YbFe4Sb12, LaFe4Sb12, low energy fluctuations, NQR, NMRThe intriguing properties of filled skutterdites, such as heavy fermion superconductivity, metal-insulator transition and multipolar ordering, have attracted comprehensive studies, and much of the fundamental nature stemmed from the peculiar crystal structure have been clarified.1 The filled skutterudites with a formula RT 4 X 12 have a structure of space group Im3, in which rare-earth atom R is filled as a guest in each cage formed by twelve ligand pnictogen atoms X which allows the 4f electrons to move by mixing with neighboring p electron orbits, giving rise to the wide variety of strongly correlated electron phenomena. Possible contribution on the physical properties from the thermal fluctuations of R in each cage has also attracted intensive interest. However, some of experimental studies suggest that the physical properties are largely affected by the existence of rare-earth atom deficiency in the material. One of the important issues being left unsolved in filled skutterudites is the effect of incomplete filling on the strongly correlated electron phenomena and the R ion motions in the cage.We have carried out 121 Sb nuclear quadrupole resonance (NQR) and 139 La nuclear magnetic resonance (NMR) measurements by using almost completely filled materials of the heavy fermion YbFe 4 Sb 12 and the related compound LaFe 4 Sb 12 prepared at high pressures and high temperatures.2 The results of present NQR/NMR study are compared with the data previously reported for the compounds with rare-earth deficiencies of about 10%. Figure 1 shows 139 La (I = 7/2) NMR lines and 121 Sb (spin I = 5/2) NQR lines of the transition between | ± 3/2 and | ± 5/2 spin levels. Each of the Lorentzian-type resonance lines in shape has a *

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Recent NMR Studies of Thermoelectric Materials

Sirusi

Ross

2017

Annual Reports on NMR Spectroscopy

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Evidence for Ferromagnetic Fluctuations in Filled Skutterudite LaFe₄Sb₁₂:Sb-NQR and La-NMR

Cited by 26 publications

References 19 publications

NMR/NQR Study of Filled Skutterudite La_0.5Co₄Sb₁₂

NMR/NQR Study of Filled Skutterudite La_0.5Co₄Sb₁₂

Effect of Rare-Earth Filling Rate for the Physical Properties of Skutterudites Investigated through NMR/NQR Measurements

Recent NMR Studies of Thermoelectric Materials

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Evidence for Ferromagnetic Fluctuations in Filled Skutterudite LaFe4Sb12:Sb-NQR and La-NMR

Cited by 26 publications

References 19 publications

NMR/NQR Study of Filled Skutterudite La0.5Co4Sb12

NMR/NQR Study of Filled Skutterudite La0.5Co4Sb12

Effect of Rare-Earth Filling Rate for the Physical Properties of Skutterudites Investigated through NMR/NQR Measurements

Recent NMR Studies of Thermoelectric Materials

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Product

Resources

About

Evidence for Ferromagnetic Fluctuations in Filled Skutterudite LaFe₄Sb₁₂:Sb-NQR and La-NMR

NMR/NQR Study of Filled Skutterudite La_0.5Co₄Sb₁₂

NMR/NQR Study of Filled Skutterudite La_0.5Co₄Sb₁₂