Synthesis and superconductivity in yttrium-cerium hydrides at high pressures
Liu-Cheng ChenT. LuoZi-Yu CaoPhilip Dalladay‐SimpsonGe HuangDi PengLili ZhangFederico A. GorelliGuo‐Hua ZhongHai‐Qing LinXiao‐Jia Chen
20
Citation
56
Reference
10
Related Paper
Citation Trend
Abstract:
Abstract Further increasing the critical temperature and/or decreasing the stabilized pressure are the general hopes for the hydride superconductors. Inspired by the low stabilized pressure associated with Ce 4 f electrons in superconducting cerium superhydride and the high critical temperature in yttrium superhydride, we carry out seven independent runs to synthesize yttrium-cerium alloy hydrides. The synthetic process is examined by the Raman scattering and X-ray diffraction measurements. The superconductivity is obtained from the observed zero-resistance state with the detected onset critical temperatures in the range of 97-141 K. The upper critical field towards 0 K at pressure of 124 GPa is determined to be between 56 and 78 T by extrapolation of the results of the electrical transport measurements at applied magnetic fields. The analysis of the structural data and theoretical calculations suggest that the phase of Y 0.5 Ce 0.5 H 9 in hexagonal structure with the space group of P 6 3 / m m c is stable in the studied pressure range. These results indicate that alloying superhydrides indeed can maintain relatively high critical temperature at relatively modest pressures accessible by laboratory conditions.Keywords:
Critical field
The superconducting parameters and upper critical field of the noncentrosymmetric superconductor BiPd have proven contentious. This material is of particular interest because it is a rare example of a $4f$-electron-free noncentrosymmetric superconductor of which crystals may be grown and cleaved, enabling surface-sensitive spectroscopies. Here, using bulk probes augmented by tunneling data on defects, we establish that the lower of the previously reported upper critical fields corresponds to the bulk transition. The material behaves as a nearly weak-coupled BCS $s$-wave superconductor, and we report its superconducting parameters as drawn from the bulk upper critical field. Possible reasons behind the order-of-magnitude discrepancy in the reported upper critical fields are discussed.
Critical field
Cite
Citations (22)
In this chapter, the properties of Type II superconductors are described. Up to the lower critical field, magnetic field is excluded from the interior of a Type II superconductor as in the case of a Type I superconductor. However, between the lower and upper critical fields, there exists a mixed state in which magnetic flux can penetrate into the interior of the superconductor and normal and superconducting regions can coexist within the material. The Ginzburg–Landau theory, to which a brief introduction is presented, perfectly describes the behavior of Type II superconductors. Relations among the coherence length, the penetration depth, the thermodynamic critical field, and the lower and upper critical fields, are presented for isotropic and anisotropic superconductors. The factors limiting the critical current densities in Type I and Type II superconductors are discussed.
Critical field
Type-II superconductor
Superconducting coherence length
Ginzburg–Landau theory
Limiting
London penetration depth
Cite
Citations (3)
Critical field
Type-II superconductor
Cite
Citations (2)
Abstract This chapter describes how the phenomenological understanding of superconductors was vastly enhanced by the Ginzburg–Landau theory. Its success rested on the fact that it could quantitatively yield the two characteristic lengths λ and ξ and address the question of boundary energy between superconducting and normal phases in terms of the Ginzburg–Landau parameter κ. for κ <1/√2, the sign of the boundary is positive and these are type I superconductors (including pure elements) where superconductivity is abruptly lost at Hc. When κ ≥1/√2, the boundary energy is negative and such materials (including impure metals and alloys) are type II superconductors. Field penetration now begins at a lower critical field Hc1 (Hc), where the bulk of the superconductivity is lost. Between the two fields, the sample is in a mixed state. Basic features of type II superconductors are discussed.
Critical field
Ginzburg–Landau theory
Type-II superconductor
Cite
Citations (0)
Experimental data on solvent extraction of cerium (III), yttrium (III), lanthanum (III) by solutions of oleinic acid in o-dimethylbenzene was obtained. The possibility of extraction sepa- ration of cerium(III), yttrium(III), lanthanum (III) from nitrate media was shown.
Lanthanum
Cerium nitrate
Cite
Citations (0)
Cite
Citations (31)
Critical field
Ginzburg–Landau theory
Cite
Citations (15)
All superconductors in a magnetic field are characterized by three critical magnetic fields: lower critical
Sequence (biology)
Cite
Citations (1)
Critical field
Lattice (music)
Cite
Citations (44)
Abstract Stepwise stability constants of the complexes of glutamic acid with cerium(III) and yttrium (III) have been determined by the Calvin‐Bjerrum pH titration technique as used by Irving and Rossotti in aqueous solution at 25° and 45°C. The values of log β 2 for cerium complexes are: 9.75 (μ = 0.1), 9.57 (μ = 0.2), 9.38 (μ = 0.3) at 25°C; and 10.90 (μ = 0.1), 10.74 (μ = 0.2), 10.64 (μ = 0.3) at 45°C. The log β 2 values for yttrium complexes at μ = 0.1 are 9.98 and 9.77 at 25° and 45°C respectively. The values of log β 2 (μ = 0.0) for cerium complexes are 10.21 and 11.24 at 25° and 45°C respectively. The increasing ionic strength of the medium decreases the stabilities of cerium complexes which are also more stable at 45° than 25°C whereas yttrium complexes are less stable at 45°C. The values of AH and ΔS are positive for cerium complexes whereas in the case of yttrium complexes, the values of ΔH are negative and those of ΔS are positive.
Cite
Citations (6)