Divalent, trivalent, and heavy fermion states in Eu compounds

Ōnuki, Yoshichika; Nakamura, Ai; Honda, Fuminori; Aoki, Dai; Tekeuchi, T.; Nakashima, Miho; Amako, Yasushi; Harima, Hisatomo; Matsubayashi, Kazuyuki; Uwatoko, Yoshiya; Kayama, Shuei; Kagayama, Tomoko; Shimizu, Katsuya; Muthu, S. Esakki; Braithwaite, D.; Salce, B.; Shibata, Hiroyuki; Yara, Tomoyuki; Ashitomi, Yousuke; Akamine, Hikaru; Tomori, K; Hedo, Masato; Nakama, Takao

doi:10.1080/14786435.2016.1218081

Cited by 44 publications

(41 citation statements)

References 30 publications

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“…[2][3][4] Comparatively less work has been done to explore the effects of pressure or doping in Eu-based intermetallics, even though Eu presents similar opportunities to tune the ground state through valence fluctuations between magnetic Eu 2+ and nonmagnetic Eu 3+ ions. 5 In this study, we explored the effects of isovalent doping in the Eu(Ga 1−x Al x ) 4 series, motivated by the wide range of apparently conflicting results observed when tuning the properties of the end compounds EuGa 4 and EuAl 4 .…”

Section: Introductionmentioning

confidence: 99%

Charge density wave behavior and order-disorder in the antiferromagnetic metallic seriesEu(Ga1−xAlx)4
Stavinoha
¹
,
Cooley
²
,
Minasian
³

et al. 2018
Phys. Rev. B
24
1
7
0
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The solid solution Eu(Ga1−xAlx)4 was grown in single crystal form to reveal a rich variety of crystallographic, magnetic, and electronic properties that differ from the isostructural end compounds EuGa4 and EuAl4, despite the similar covalent radii and electronic configurations of Ga and Al.Here we report the onset of magnetic spin reorientation and metamagnetic transitions for x = 0 − 1 evidenced by magnetization and temperature-dependent specific heat measurements. TN changes non-monotonously with x, and it reaches a maximum around 20 K for x = 0.50, where the a lattice parameter also shows an extreme (minimum) value. Anomalies in the temperature-dependent resistivity consistent with charge density wave behavior exist for x = 0.50 and 1 only. Density functional theory calculations show increased polarization between the Ga−Al covalent bonds in the x = 0.50 structure compared to the end compounds, such that crystallographic order and chemical pressure are proposed as the causes of the charge density wave behavior.

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Section: Introductionmentioning

confidence: 99%

Charge density wave behavior and order-disorder in the antiferromagnetic metallic seriesEu(Ga1−xAlx)4
Stavinoha
¹
,
Cooley
²
,
Minasian
³

et al. 2018
Phys. Rev. B
24
1
7
0
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“…However, the energy difference between Eu 2+ and the non-magnetic Eu 3+ (4f 6 , J=0) valence state is not so large 5 and is reachable by applying external pressure or chemical substitution. Indeed, amongst the most extensively studied Eu-compounds series with the ThCr 2 Si 2 -type crystal structure, pressure or chemical substitution controlled first-order valence transitions and valence fluctuations are frequently reported 6 . In the Eu(Pd 1−x Au x ) 2 Si 2 system, EuAu 2 Si 2 possesses a Eu 2+ valence state and exhibits antiferromagnetic ordering below the Néel temperature (T N ) of ∼ 15.5 K 7 .…”

Section: Introductionmentioning

confidence: 99%

Bulk electronic structure of non-centrosymmetric EuTGe3 ( T=Co , Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

et al. 2018

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Non-centrosymmetric EuT Ge3 (T =Co, Ni, Rh, and Ir) possesses magnetic Eu 2+ ions and antiferromagnetic ordering appears at low temperatures. Transition metal substitution leads to changes of the unit cell volume and of the magnetic ordering. However, the magnetic ordering temperature does not scale with the volume change and the Eu valence is expected to remain divalent. Here we study the bulk electronic structure of non-centrosymmetric EuT Ge3 (T =Co, Ni, Rh, and Ir) by hard x-ray photoelectron spectroscopy. The Eu 3d core level spectrum confirms the robust Eu 2+ valence state against the transition metal substitution with a small contribution from Eu 3+ . The estimated Eu mean-valence is around 2.1 in these compounds as confirmed by multiplet calculations. In contrast, the Ge 2p spectrum shifts to higher binding energy upon changing the transition metal from 3d to 4d to 5d elements, hinting of a change in the Ge-T bonding strength. The valence bands of the different compounds are found to be well reproduced by ab initio band structure calculations.

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“…Here, S , L, and J are the total spin, total orbital, and total angular momenta, respectively. It is interesting that the number of intermetallic compounds with Eu 3+ found thus far at ambient pressure is much smaller than that with Eu 2+ or the intermediate valence state, 22) even though most rare-earth ions are usually trivalent in their compounds. The valence state of the Eu ion can be tuned easily by external parameters, such as temperature and pressure, because the energy difference between the two valence states is relatively small.…”

Section: Introductionmentioning

confidence: 99%

Magnetic, Transport, and Phonon Properties of the Trivalent Eu Metallic Compound EuBe₁₃

et al. 2019

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Magnetic susceptibility χ, specific heat C, and electrical resistivity ρ measurements have been performed on singlecrystal EuBe 13 in the temperature range between 2 and 300 K to investigate its phonon property and the valence state of the Eu ion. The obtained χ(T ) curves obey a typical Van Vleck susceptibility for Eu 3+ with a nonmagnetic ground state in the entire measured temperature range. In the case of C(T ), we observed the coexistence of Debye and Einstein phonon modes with characteristic Debye and Einstein temperatures of θ D ∼ 835 K and θ E ∼ 167 K, respectively, which are in good agreement with those previously reported for other isostructural MBe 13 compounds (M = rare earths and actinides). The ρ(T ) curve for EuBe 13 shows an unusual T 3 -like dependence at low temperatures, as also observed for the nonmagnetic isostructural compound LaBe 13 , which can be reproduced well by calculations based on electron-phonon scattering using the estimated θ D and θ E . We also summarized the relationship between the Eu-valence state and the free distance between the Eu ion and the first-nearest-neighbor atoms in several Eu-based cubic compounds, and argued that EuBe 13 takes the Eu 3+ state despite its larger free distance than other Eu 3+ compounds.

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Divalent, trivalent, and heavy fermion states in Eu compounds

Cited by 44 publications

References 30 publications

Charge density wave behavior and order-disorder in the antiferromagnetic metallic seriesEu(Ga1−xAlx)4
Stavinoha
¹
,
Cooley
²
,
Minasian
³

et al. 2018
Phys. Rev. B
24
1
7
0
View full text Add to dashboard Cite

Charge density wave behavior and order-disorder in the antiferromagnetic metallic seriesEu(Ga1−xAlx)4
Stavinoha
¹
,
Cooley
²
,
Minasian
³

et al. 2018
Phys. Rev. B
24
1
7
0
View full text Add to dashboard Cite

Bulk electronic structure of non-centrosymmetric EuTGe3 ( T=Co , Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

Magnetic, Transport, and Phonon Properties of the Trivalent Eu Metallic Compound EuBe₁₃

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Divalent, trivalent, and heavy fermion states in Eu compounds

Cited by 44 publications

References 30 publications

Charge density wave behavior and order-disorder in the antiferromagnetic metallic seriesEu(Ga1−xAlx)4Stavinoha1, Cooley2, Minasian3 et al. 2018Phys. Rev. B24170View full textAdd to dashboardCite

Charge density wave behavior and order-disorder in the antiferromagnetic metallic seriesEu(Ga1−xAlx)4Stavinoha1, Cooley2, Minasian3 et al. 2018Phys. Rev. B24170View full textAdd to dashboardCite

Bulk electronic structure of non-centrosymmetric EuTGe3 ( T=Co , Ni, Rh, Ir) studied by hard x-ray photoelectron spectroscopy

Magnetic, Transport, and Phonon Properties of the Trivalent Eu Metallic Compound EuBe13

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Charge density wave behavior and order-disorder in the antiferromagnetic metallic seriesEu(Ga1−xAlx)4
Stavinoha
¹
,
Cooley
²
,
Minasian
³

et al. 2018
Phys. Rev. B
24
1
7
0
View full text Add to dashboard Cite

Charge density wave behavior and order-disorder in the antiferromagnetic metallic seriesEu(Ga1−xAlx)4
Stavinoha
¹
,
Cooley
²
,
Minasian
³

et al. 2018
Phys. Rev. B
24
1
7
0
View full text Add to dashboard Cite

Magnetic, Transport, and Phonon Properties of the Trivalent Eu Metallic Compound EuBe₁₃