Charge Fluctuations in the NdO1−xFxBiS2 Superconductors

Athauda, Anushika; Mizuguchi, Yoshikazu; Nagao, Masanori; Neuefeind, Jöerg C.; Louca, Despina

doi:10.7566/jpsj.86.124718

Cited by 11 publications

(17 citation statements)

References 26 publications

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“…It is consistent with the isotope effect; no isotope effect was observed for the LaO0.6F0.4Bi(S,Se)2 samples with 76 Se and 80 Se isotopes [31]. proposed by theoretical and experimental studies [28,29,32,39], may occur in the BiCh2-based system.…”

supporting

confidence: 84%

“…It is worth noting that U11 for the Bi sites slightly increases with the decrease of the RE 3+ radius. Recently, Athauda et al proposed that the increase in the in-plane displacement of Bi may be attributed with the superconductivity in NdO1-xFxBiS2, while the in-plane displacement of S1 would induce carrier localization [29]. Our analysis also suggests that the increase of the in-plane displacement of the Bi sites may be related with the enhanced Tc for RE = Pr and Nd.…”

supporting

confidence: 60%

“…1(b)) can be attributed with the emergence of superconductivity in the RE-substituted systems. Neutron diffraction and pair distribution function analysis revealed the presence of the in-plane disorder and its relationship with the superconductivity, where RE is La or Nd [28,29]. In addition, EXAFS measurements reveled a suppression of the Bi-S1-bond-disorder with the decrease of the RE 3+ radius [30].…”

mentioning

confidence: 93%

“…If this is valid, then the Tc increases when the phonon frequency decreases with the increase of the amplitude of the S1 vibration along the c-axis. proposed by theoretical and experimental studies [28,29,32,39], may occur in the BiCh2-based system.In conclusion, we investigated the crystal structure and anisotropic displacement parameters of REO0.5F0.5BiS2 with RE = La, Ce, Pr, and Nd, where bulk superconductivity is induced by substitutions with a smaller-radius RE, such as Pr or Nd. With the decrease of the RE 3+ ionic radius, the lattice constant a and in-plane Bi-S1 distance monotonically decreased, which generated the in-plane chemical pressure effect.…”

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confidence: 99%

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Evolution of Anisotropic Displacement Parameters and Superconductivity with Chemical Pressure in BiS₂-Based REO_0.5F_0.5BiS₂ (RE = La, Ce, Pr, and Nd)

et al. 2018

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In order to understand the mechanisms behind the emergence of superconductivity by the chemical pressure effect in REO0.5F0.5BiS2 (RE = La, Ce, Pr, and Nd), where bulk superconductivity is induced by the substitutions with a smaller-radius RE, we performed synchrotron powder X-ray diffraction, and analyzed the crystal structure and anisotropic displacement parameters. With the decrease of the RE 3+ ionic radius, the in-plane disorder of the S1 sites significantly decreased, very similar to the trend observed in the Se-substituted systems: LaO0.5F0.5BiS2-xSex and Eu0.5La0.5FBiS2-xSex. Therefore, the emergence of bulk superconductivity upon the suppression of the in-plane disorder at the chalcogen sites is a universal scenario for the BiCh2-based superconductors. In addition, we indicated that the amplitude of vibration along the c-axis of the in-plane chalcogen sites may be related to the Tc in the BiCh2-based superconductors. . In addition, the observed temperature dependence of the electrical resistivity was not metallic-like; it showed a weakly localized behavior in LaO1-xFxBiS2, although band calculations suggested that the electron-doped LaO1-xFxBiS2 should be metal [4,5,12]. These results suggested that the doped electrons were localized by the effect of structural disorder.In order to induce bulk superconductivity in LaO1-xFxBiS2, high pressure effects can be employed.The application of an external pressure induces bulk superconductivity with a Tc of ~10 K [13][14][15]. In addition, samples annealed under a high pressure (~2 GPa) also exhibit bulk superconductivity with aTc of ~10 K [2,[16][17][18]. The emergence of bulk superconductivity and increase of Tc in the highpressure phase can be attributed to the structural phase transition from the tetragonal low-Tc phase to the monoclinic high-Tc phase [13].Another approach to induce bulk superconductivity in the LaO1-xFxBiS2 system is to introduce a chemical pressure by an isovalent substitution, such as Ch (Ch: S, Se) and/or RE site substitutions. In LaO0.5F0.5BiS2-xSex, the substitutions of Se for the S sites induces bulk superconductivity with a Tc of ~3.8 K [19,20]. Another isovalent substitution is the RE site substitution. With the decrease of the RE 3+ (mean) ionic radius in REO0.5F0.5BiS2, the BiS2 layer becomes compressed, in particular along the ab-plane direction, and bulk superconductivity is induced [21]. As the isovalent substitution does not significantly affect the carrier concentration, the structural optimization induces superconductivity in the Ch-and RE-substituted systems. In order to analyze the essential factor for the emergence of the superconductivity, we considered the commonality of the chemical pressure effects between the Ch-and RE substitutions, by introducing the concept of an in-plane chemical pressure [22].The emergence of the bulk superconductivity in the LaO0.5F0.5BiS2-xSex system was explained by the decrease in the in-plane disorder of the chalcogen sites with the increase of the Se content, which was detected thro...

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confidence: 60%

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confidence: 93%

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confidence: 99%

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confidence: 99%

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Evolution of Anisotropic Displacement Parameters and Superconductivity with Chemical Pressure in BiS₂-Based REO_0.5F_0.5BiS₂ (RE = La, Ce, Pr, and Nd)

et al. 2018

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The local structure of self-doped BiS₂-based layered systems as a function of temperature

Pugliese

Paris

Capone

et al. 2020

Phys. Chem. Chem. Phys.

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Suppression of structural instability in LaOBiS_2−xSe_x by Se substitution

Paris

Mizuguchi

Wakita

et al. 2018

J. Phys.: Condens. Matter

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Isovalent substitution of S by Se in LaOBiS 2−x Se x has a substantial effect on its electronic structure and thermoelectric properties. To investigate the possible role of BiS 2 structural instability, we have studied the local structure of LaOBiS 2−x Se x ( x = 0.0, 1.0) using temperature dependent Bi L 3 -edge extended x-ray absorption fine structure measurements. The results reveal that the local structure of the two compounds is significantly different. The BiS 2 sub-lattice is largely distorted in LaOBiS 2 (x = 0.0), with two in-plane Bi-S1 distances separated by ∼0.4 Å instead LaOBiSSe (x = 1.0) showing much smaller local disorder with two in-plane Bi-Se distances in the plane being separated by ∼0.2 Å. Temperature dependent study shows that the two Bi-S1 distances are characterized by different bond strength in LaOBiS 2 (x = 0.0) while it is similar for the Bi-Se distances in LaOBiSSe (x = 1.0). The out of plane Bi-S2 bond is harder in LaOBiSSe indicating that the structural instability of BiS 2 layer has large effect on the out-of-plane atomic correlations. The results suggest that the local structure of LaOBiS 2−x Se x is an important factor to describe differing electronic and thermal transport of the two compounds.

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Charge Fluctuations in the NdO₁₋_xF_xBiS₂ Superconductors

Cited by 11 publications

References 26 publications

Evolution of Anisotropic Displacement Parameters and Superconductivity with Chemical Pressure in BiS₂-Based REO_0.5F_0.5BiS₂ (RE = La, Ce, Pr, and Nd)

Evolution of Anisotropic Displacement Parameters and Superconductivity with Chemical Pressure in BiS₂-Based REO_0.5F_0.5BiS₂ (RE = La, Ce, Pr, and Nd)

The local structure of self-doped BiS₂-based layered systems as a function of temperature

Suppression of structural instability in LaOBiS_2−xSe_x by Se substitution

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Charge Fluctuations in the NdO1−xFxBiS2 Superconductors

Cited by 11 publications

References 26 publications

Evolution of Anisotropic Displacement Parameters and Superconductivity with Chemical Pressure in BiS2-Based REO0.5F0.5BiS2 (RE = La, Ce, Pr, and Nd)

Evolution of Anisotropic Displacement Parameters and Superconductivity with Chemical Pressure in BiS2-Based REO0.5F0.5BiS2 (RE = La, Ce, Pr, and Nd)

The local structure of self-doped BiS2-based layered systems as a function of temperature

Suppression of structural instability in LaOBiS2−x Se x by Se substitution

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Charge Fluctuations in the NdO₁₋_xF_xBiS₂ Superconductors

Evolution of Anisotropic Displacement Parameters and Superconductivity with Chemical Pressure in BiS₂-Based REO_0.5F_0.5BiS₂ (RE = La, Ce, Pr, and Nd)

Evolution of Anisotropic Displacement Parameters and Superconductivity with Chemical Pressure in BiS₂-Based REO_0.5F_0.5BiS₂ (RE = La, Ce, Pr, and Nd)

The local structure of self-doped BiS₂-based layered systems as a function of temperature

Suppression of structural instability in LaOBiS_2−xSe_x by Se substitution