Effects of Magnetic Field and Pressure on the Valence-Fluctuating Antiferromagnetic Compound EuPt<sub>2</sub>Si<sub>2</sub>

Takeuchi, Tetsuya; Yara, Tomoyuki; Ashitomi, Yousuke; Iha, Wataru; Kakihana, Masashi; Nakashima, Miho; Amako, Yasushi; Honda, Fuminori; Homma, Yoshiya; Aoki, Dai; Uwatoko, Yoshiya; Kida, Takanori; Tahara, Time; Hagiwara, Masayuki; Haga, Yoshinori; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

doi:10.7566/jpsj.87.074709

Cited by 16 publications

(3 citation statements)

References 55 publications

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“…valence transition at T V = 200 K [9,10] while EuRh 2 Si 2 is an antiferromagnet where applied pressure abruptly changes the Eu valence from 2+ to 3+ near 1 GPa [11][12][13]. EuNi 2 P 2 [14,15], EuIr 2 Si 2 [16], EuPt 2 Si 2 [17] and EuCu 2 (Ge 1−x Si x ) 2 [18] also exhibit behavior that resembles that of a typical heavy fermion Kondo lattice. Based on such observations, it is appealing to organize these materials within a Doniachlike phase diagram [4,19], where tuning parameters such as applied pressure and/or chemical substitution adjust both the Eu valence and the relative strengths of the RKKY and Kondo interactions [20][21][22][23].…”

Section: Introductionmentioning

confidence: 97%

Electronic and magnetic properties of EuNi_2−δSb₂ structural variants

Nelson

Jayasinghe

Graf

et al. 2020

J. Phys.: Condens. Matter

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X-ray diffraction, magnetic susceptibility, magnetization, heat capacity and electrical resistivity results are reported for single crystals of two structural variants of EuNi 2−δ Sb 2 that crystallize in the CaBe 2 Ge 2 and ThCr 2 Si 2 -type structures. While the former occurs with a stoichiometric ratio, the latter exhibits a Ni site vacancy (δ = 0.36). Both systems exhibit similar magnetic behavior at elevated temperatures, where there is an isotropic Curie-Weiss temperature dependence that indicates an antiferromagnetic exchange interaction between divalent europium ions, although it is stronger for the CaBe 2 Ge 2 -variant. At low temperatures, the differing structural environments that surround the Eu ions result in distinct ordering behavior. The CaBe 2 Ge 2 -variant orders antiferromagnetically near T N1 = 6.9 K and then undergoes a rst order phase transition at T M = 4.6 K. The ThCr 2 Si 2 -variant exhibits simpler behavior, with antiferromagnetic ordering at T N2 = 5.6 K. For both compounds, an applied magnetic eld suppresses the ordering temperatures and induce metamagnetic phase transitions, while applied pressure causes the ordering temperatures to increase. From these results, EuNi 2−δ Sb 2 emerges as a useful system in which to study the impact of structural variation on magnetism in a Eu-based metal.

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Section: Introductionmentioning

confidence: 97%

Electronic and magnetic properties of EuNi_2−δSb₂ structural variants

Nelson

Jayasinghe

Graf

et al. 2020

J. Phys.: Condens. Matter

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“…Recent experimental activities have definitely clarified a rich variety of low-temperature properties of the Eu compounds; one can now encounter exotic antiferromagnetic orders, quantum critical phenomena, heavy fermions (HF), and valence transition or crossover phenomena in several Eu compounds, when controlling the pressure and/or the doping rate [1][2][3][4][5][6][7][8][9]. As a basis to clarify the microscopic origin of such interesting physics of the Eu system, we have introduced the Eu-based impurity Anderson model in a previous paper [10] and have shown that the total singlet ground state is realized in the entire region between the divalent and trivalent Eu ion.…”

Section: Introductionmentioning

confidence: 99%

Field-induced local Fermi-liquid states in the underscreened Kondo model for Eu compounds

Kuniyoshi

Shiina

2023

SciPost Phys. Proc.

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We have studied an underscreened Kondo model for the impurity spin S=7/2S=7/2 capturing the 4f4f characteristics of a nearly divalent Eu ion. By using the numerical renormalization group method, it is shown that an unusual heavy-fermion state is induced from the underscreened spin state when a weak crystal field is introduced. It is also found that the application of the magnetic field enhances the effective mass of the heavy fermions, reflecting the field-induced level crossing of the spin states. We will discuss the mechanism of these mass enhancements in terms of a realization of the two-stage Kondo effect.

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“…The antiferromagnetic transition temperature T N of EuPt 2 Si 2 decreases continuously with increasing pressure without showing the valence transition, and T N = 0 at P V ≃ 4 GPa. 22,23) Unlike the divalent Eu state, the trivalent Eu state is nonmagnetic (J = 0, S = L = 3). EuPd 3 is one of the few Eu compounds in which the Eu ion becomes trivalent.…”

Section: Introductionmentioning

confidence: 99%

Microscopic Observation of Heavy Quasiparticle Formation in the Intermediate Valence Compound EuNi₂P₂: ³¹P NMR Study

et al. 2018

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We report 31 P NMR measurements under various magnetic fields up to 7 T for the intermediate valence compound EuNi 2 P 2 , which shows heavy electronic states at low temperatures. In the high-temperature region above 40 K, the Knight shift followed the Curie-Weiss law reflecting localized 4 f states. In addition, the behavior corresponding to the temperature variation of the average valence of Eu was observed in the nuclear spin-lattice relaxation rate 1/T 1 . With the occurrence of the Kondo effect, 1/T 1 was clearly reduced below 40 K, and the Knight shift becomes almost constant at low temperatures. From these results, the formation of heavy quasiparticles by the hybridization of Eu 4 f electrons and conduction electrons was clarified from microscopic viewpoints. Furthermore, a characteristic spin fluctuation was observed at low temperatures, which would be associated with valence fluctuations caused by the intermediate valence state of EuNi 2 P 2 .

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Effects of Magnetic Field and Pressure on the Valence-Fluctuating Antiferromagnetic Compound EuPt₂Si₂

Cited by 16 publications

References 55 publications

Electronic and magnetic properties of EuNi_2−δSb₂ structural variants

Electronic and magnetic properties of EuNi_2−δSb₂ structural variants

Field-induced local Fermi-liquid states in the underscreened Kondo model for Eu compounds

Microscopic Observation of Heavy Quasiparticle Formation in the Intermediate Valence Compound EuNi₂P₂: ³¹P NMR Study

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Effects of Magnetic Field and Pressure on the Valence-Fluctuating Antiferromagnetic Compound EuPt2Si2

Cited by 16 publications

References 55 publications

Electronic and magnetic properties of EuNi2−δ Sb2 structural variants

Electronic and magnetic properties of EuNi2−δ Sb2 structural variants

Field-induced local Fermi-liquid states in the underscreened Kondo model for Eu compounds

Microscopic Observation of Heavy Quasiparticle Formation in the Intermediate Valence Compound EuNi2P2: 31P NMR Study

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Effects of Magnetic Field and Pressure on the Valence-Fluctuating Antiferromagnetic Compound EuPt₂Si₂

Electronic and magnetic properties of EuNi_2−δSb₂ structural variants

Electronic and magnetic properties of EuNi_2−δSb₂ structural variants

Microscopic Observation of Heavy Quasiparticle Formation in the Intermediate Valence Compound EuNi₂P₂: ³¹P NMR Study