Magnetic properties and hyperfine interactions in EuCu2Ge2 single crystals

Wang, P.; Stadnik, Z. M.; Żukrowski, J.; Cho, B.K.; Kim, J.Y.

doi:10.1016/j.ssc.2010.09.003

Cited by 11 publications

(6 citation statements)

References 28 publications

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“…In the case of EuCu 2 Ge 2 , the effective magnetic moment µ eff , obtained from the inverse magnetic susceptibility 8) and Mössbauer spectroscopy, 10) is close to the free-ion value µ eff = 7.94µ B /Eu of Eu 2+ . T N = 15 K at ambient pressure increases as a function of pressure, becomes a maximum of T N = 27 K at 6 GPa, and decreases steeply toward zero at a pressure between P = 6 and 7 GPa.…”

supporting

confidence: 54%

Quantum Criticality of Valence Transition for the Unique Electronic State of Antiferromagnetic Compound EuCu₂Ge₂

et al. 2020

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The effect of pressure on the unique electronic state of the antiferromagnetic (AF) compound EuCu 2 Ge 2 has been measured in a wide temperature range from 10 mK to 300 K by electrical resistivity measurements up to 10 GPa. The Néel temperature of T N = 15 K at ambient pressure increases monotonically with increasing pressure and becomes a maximum of T N = 27 K at 6.2 GPa but suddenly drops to zero at P c ≃ 6.5 GPa, suggesting the quantum critical point (QCP) of the valence transition of Eu from a nearly divalent state to that with trivalent weight.The ρ mag0 and A values obtained from the low-temperature electrical resistivity based on the Fermi liquid relation of ρ mag = ρ mag0 + AT 2 exhibit huge and sharp peaks around P c . The exponent n obtained from the power law dependence ρ mag = ρ mag0 + BT n is clearly less than 1.5 at P = P c ≃ 6. 5 GPa, which is expected at the AF-QCP. These results indicate that P c coincides with P v , corresponding to the quantum criticality of the valence transition pressure P v .The electronic specific heat coefficient γ, estimated from the generalized Kadowaki-Woods relation, is about 510 mJ/(mol·K 2 ) around P c , suggesting the formation of a heavy-fermion state.Most Eu compounds including Eu 2 Ni 3 Ge 5 1) and EuRhSi 3 1) order magnetically because of the divalent electronic state of Eu 2+ . Valence instability often occurs in Eu compounds, from the divalent electronic state of Eu 2+ (4 f 7 : S =7/2, L = 0, and J =7/2) at high temperatures to the nearly nonmagnetic electronic state (4 f 6 in Eu 3+ : S = L = 3, and J

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confidence: 54%

Quantum Criticality of Valence Transition for the Unique Electronic State of Antiferromagnetic Compound EuCu₂Ge₂

et al. 2020

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“…Three types of superstructures of BaAl 4 with REM 1 M 2 composition have been reported: (a) ThCr 2 Si 2 type (tetragonal, I 4/ mmm ), (b) CeAl 2 Ga 2 type (tetragonal, I 4/ mmm ), and (c) CaBe 2 Ge 2 type (tetragonal, P 4/ mmm ) . The crystal structure of EuCu 2 Ge 2 was previously reported only via powder XRD refinement. ,,,− The close relation between these structure types is already found in EuZn 2 Ge 2 , , which was reported for both types CeAl 2 Ga 2 (tetragonal I 4/ mmm with lattice parameters of a = b = 4.348 Å and c = 10.589 Å) and CaBa 2 Ge 2 (tetragonal P 4/ mmm with lattice parameters of a = b = 4.309 Å and c = 10.792 Å).…”

Section: Results and Discussionmentioning

confidence: 59%

“…Because we have obtained a new compound in the Eu–Ag–In family, we extended our research to the Eu–Cu–Ge series. There is only one compound (EuCu 2 Ge 2 ) that has been reported so far in this series, which was reported to crystallize in the tetragonal crystal system. − The divalent nature of Eu atoms in EuCu 2 Ge 2 has been proven via 151 Eu Mössbauer spectroscopy and magnetic susceptibility measurements, but Banik et al proposed the mixed valent nature through X-ray absorption spectroscopy studies . Later, compound Eu 3 Cu 2 In 9 was synthesized by the high-frequency induction heating (HFIH) method.…”

Section: Introductionmentioning

confidence: 97%

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Metal Flux Growth, Structural Relations, and Physical Properties of EuCu₂Ge₂ and Eu₃T₂In₉ (T = Cu and Ag)

et al. 2016

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Single crystals (SCs) of the compounds EuAgIn and EuCuGe were synthesized through the reactions run in liquid indium. EuAgIn crystallizes in the LaAl structure type [orthorhombic space group (SG) Immm] with the lattice parameters: a = 4.8370(1) Å, b = 10.6078(3) Å, and c = 13.9195(4) Å. EuCuGe crystallizes in the tetragonal ThCrSi structure type (SG I4/mmm) with the lattice parameters: a = b = 4.2218(1) Å, and c = 10.3394(5) Å. The crystal structure of EuAgIn is comprised of edge-shared hexagonal rings consisting of indium. The one-dimensional chains of In rings are shared through the edges, which are further interconnected with other six-membered rings forming a three-dimensional (3D) stable crystal structure along the bc plane. The crystal structure of EuCuGe can be explained as the complex [CuGe] polyanionic network embedded with Eu ions. These polyanionic networks present in the crystal structure of EuCuGe are shared through the edges of the 011 plane containing Cu and Ge atoms, resulting in a 3D network. The structural relationship between EuTIn and EuCuGe has been discussed in detail, and we conclude that EuTIn is the metal deficient variant of EuCuGe. The magnetic susceptibilities of EuTIn (T = Cu and Ag) and EuCuGe were measured between 2 and 300 K. In all cases, magnetic susceptibility data followed Curie-Weiss law above 150 K. Magnetic moment values obtained from the measurements indicate the probable mixed/intermediate valent behavior of the europium atoms, which was further confirmed by X-ray absorption studies and bond distances around the Eu atoms. Electrical resistivity measurements suggest that EuTIn and EuCuGe are metallic in nature.

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“…It has been shown that growth conditions can profoundly affect the magnetic properties of the Eu in both EuCu 2 Si 2 [1,22] and EuCu 2 Ge 2 [5,23]. In the silicides, EuCu 2 Si 2 [1] and EuMn 2 Si 2 [3], the valence of the Eu is strongly temperature dependent, becoming more divalent with increasing temperature.…”

Section: Discussionmentioning

confidence: 99%

Europium and manganese magnetic ordering in EuMn₂Ge₂

Ryan

Rejali

Cadogan

et al. 2016

J. Phys.: Condens. Matter

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The antiferromagnetic structures of both the manganese and europium sublattices in EuMn2Ge2 have been determined using thermal neutron diffraction. T(N)(Mn) = 714(5) K with the 3.35(5) μ(B) (at 285 K) Mn moments ordering according to the I4'/m'm'm space group. The Eu order is incommensurate with the 6.1(2) μ(B) (at 3.6 K) Eu moments oriented parallel to the c-axis with a propagation vector of k = [0.153(2) 0 0]. Both neutron diffraction and (151)Eu Mössbauer spectroscopy reveal evidence of magnetic short-range ordering of the Eu sublattice around and above T(N)(Eu) ∼ 10 K. The ordering temperature of the Eu sublattice is strongly affected by the sample's thermal history and rapid quenching from the melting point may lead to a complete suppression of that ordering.

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Magnetic properties and hyperfine interactions in EuCu2Ge2 single crystals

Cited by 11 publications

References 28 publications

Quantum Criticality of Valence Transition for the Unique Electronic State of Antiferromagnetic Compound EuCu₂Ge₂

Quantum Criticality of Valence Transition for the Unique Electronic State of Antiferromagnetic Compound EuCu₂Ge₂

Metal Flux Growth, Structural Relations, and Physical Properties of EuCu₂Ge₂ and Eu₃T₂In₉ (T = Cu and Ag)

Europium and manganese magnetic ordering in EuMn₂Ge₂

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Magnetic properties and hyperfine interactions in EuCu2Ge2 single crystals

Cited by 11 publications

References 28 publications

Quantum Criticality of Valence Transition for the Unique Electronic State of Antiferromagnetic Compound EuCu2Ge2

Quantum Criticality of Valence Transition for the Unique Electronic State of Antiferromagnetic Compound EuCu2Ge2

Metal Flux Growth, Structural Relations, and Physical Properties of EuCu2Ge2 and Eu3T2In9 (T = Cu and Ag)

Europium and manganese magnetic ordering in EuMn2Ge2

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Quantum Criticality of Valence Transition for the Unique Electronic State of Antiferromagnetic Compound EuCu₂Ge₂

Quantum Criticality of Valence Transition for the Unique Electronic State of Antiferromagnetic Compound EuCu₂Ge₂

Metal Flux Growth, Structural Relations, and Physical Properties of EuCu₂Ge₂ and Eu₃T₂In₉ (T = Cu and Ag)

Europium and manganese magnetic ordering in EuMn₂Ge₂