Pressure-Induced Superconductivity in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>CaLi</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

Matsuoka, Toshifumi; Debessai, M.; Hamlin, J. J.; Gangopadhyay, A. K.; Schilling, J. S.; Shimizu, Katsuya

doi:10.1103/physrevlett.100.197003

Cited by 29 publications

(29 citation statements)

References 19 publications

(35 reference statements)

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“…Furthermore, the calculated T c is in good agreement with experimental measurements. Our results suggest that the measured superconductivity [11] is from the CaLi 2 compound, and is not contaminated by decomposition into the elements.…”

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confidence: 67%

“…It was also predicted that CaLi 2 could be a potential superconductor under pressure due to the high density of states at Fermi level, the high dynamical scale of Li, and the favorable interlayer phonons. Superconductivity was subsequently observed in CaLi 2 at pressures above 11 GPa [11] with a maximum T c of 13 K near 40 GPa. Debessai et al [12] measured the x-ray diffraction patterns of CaLi 2 up to 54 GPa and found that hexagonal Laves-type CaLi 2 undergoes a phase transition above 23 GPa and completely transforms into an orthorhombic phase at 46 GPa.…”

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confidence: 98%

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Novel High Pressure Structures and Superconductivity ofCaLi2

Xie

Oganov

2010

Phys. Rev. Lett.

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Using evolutionary methodology for crystal structure prediction, we explore high-pressure phases of CaLi2, a compound made of two elements that show anomalies upon compression. In addition to the known low-pressure Laves phases, we find two novel structures with space groups C2/c and P2{1}/c, stable at pressure ranges of 35-54 GPa and 54-105 GPa, respectively. It is found that decomposition into pure elements is energetically favorable at pressures of 20-35 GPa and above 105 GPa. Such decomposition-recombination-decomposition oscillating behavior with pressure is predicted for the first time in a binary compound. The C2/c and P2{1}/c phases are predicted to be superconductors, and the calculated T{c} of approximately 15 K at 45 GPa is in good agreement with experiment.

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confidence: 67%

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confidence: 98%

Novel High Pressure Structures and Superconductivity ofCaLi2

Xie

Oganov

2010

Phys. Rev. Lett.

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“…In material synthesis, pressure adds a new dimension in creating exotic alloys and properties [615][616][617][618][619]. The formation of extended solids (polymers) is a common observation under HP, e.g., polymeric cg-N [587,620].…”

Section: High Pressure Chemistrymentioning

confidence: 99%

High-pressure studies with x-rays using diamond anvil cells

2016

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Pressure profoundly alters all states of matter. The symbiotic development of ultrahighpressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials' properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields. These HP studies include: HP x-ray emission spectroscopy, which provides information on the filled electronic states of HP samples; HP x-ray Raman spectroscopy, which probes the HP chemical bonding changes of light elements; HP electronic inelastic x-ray scattering spectroscopy, which accesses high energy electronic phenomena, including electronic band structure, Fermi surface, excitons, plasmons, and their dispersions; HP resonant inelastic x-ray scattering spectroscopy, which probes shallow core excitations, multiplet structures, and spin-resolved electronic structure; HP nuclear resonant x-ray spectroscopy, which provides phonon densities of state and time-resolved Mössbauer information; HP x-ray imaging, which provides information on hierarchical structures, dynamic processes, and internal strains; HP x-ray diffraction, which determines the fundamental structures and densities of single-crystal, polycrystalline, nanocrystalline, and non-crystalline materials; and HP radial x-ray diffraction, which yields deviatoric, elastic and rheological information. Integrating these tools with hydrostatic or uniaxial pressure media, laser and resistive heating, and cryogenic cooling, has enabled investigations of the structural, vibrational, electronic, and magnetic properties of materials over a wide range of pressure-temperature conditions.

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“…For measurements to ambient temperature the warming rate was typically 1-2 K/min, whereas in determinations of the superconducting transition temperature the rate was slowed to ∼ 1 K/h. Further details of the DAC techniques used in the electrical resistivity [19] and ac susceptibility [3,14,20] measurements are given elsewhere.…”

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confidence: 99%

Pressure-induced superconductivity in europium metal

Debessai

Matsuoka

Hamlin

et al. 2010

J. Phys.: Conf. Ser.

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Divalent Eu (4f 7 , J = 7/2) possesses a strong local magnetic moment which suppresses superconductivity. Under sufficient pressure it is anticipated that Eu will become trivalent (4f 6 , J = 0) and a weak Van Vleck paramagnet, thus opening the door for a possible superconducting state, in analogy with Am metal (5f 6 , J = 0) which superconducts at 0.79 K. We present ac susceptibility and electrical resistivity measurements on Eu metal for temperatures 1.5 -297 K to pressures as high as 142 GPa. At approximately 80 GPa Eu becomes superconducting at T c ≃ 1.8 K; T c increases linearly with pressure to 2.75 K at 142 GPa. Eu metal thus becomes the 53 rd known elemental superconductor in the periodic table.Bernd Matthias once mused that all nonmagnetic metals might become superconducting, if only they be cooled to a sufficiently low temperature [1]. Of the 92 naturally occurring elements in the periodic table, there are 30 known elemental superconductors at ambient pressure and 22 more that become superconducting under high pressure [2]. An intriguing question is whether the remaining 40 elemental solids become superconducting in some temperature/pressure range. One could, in fact, pose this same question for all solids.Across the entire lanthanide series, only its first member, La, superconducts at ambient pressure. The reasons for this appear to be twofold: (1) the local-moment magnetism in all lanthanides except La, Yb, and Lu leads to strong pair-breaking effects, and (2) as for non-superconducting Sc or Y, the relatively weak d-character of the conduction electrons for heavy lanthanides like Lu results in an only diminutive pairing interaction. Since compressing the lattice enhances the d-electron concentration, it is not surprising that Sc, Y, and Lu all become superconducting under pressure [3]; indeed, the vast majority of transition metals superconduct.In contrast, the pressure-induced superconductivity observed for Ce metal above 2 GPa arises from the suppression of its magnetism [4]. The fact that all lanthanides other than La, Ce, and Lu do not superconduct under pressure, in spite of their enhanced d-electron concentration, is a tribute to the stability of their strong local-moment magnetism. At sufficiently high pressures, however, one would anticipate that the lanthanide valence should increase as electrons are successively squeezed out of the 4f shell into the s, p, d-conduction band. The first two lanthanide metals to do this would likely be Eu and Yb since both are divalent at ambient pressure, in contrast to all others which are trivalent.Whereas trivalent Yb would exhibit a strong local magnetic moment by virtue of its 4f 13 configuration with J = L + S = 3 + 1 2 = 7/2, trivalent Eu would be left with a 4f 6 electron shell where S = L = 3 and thus J = L − S = 0. Under sufficient pressure, therefore, the divalent antiferromagnet Eu would be expected to become a trivalent weak Van Vleck paramagnet and a good candidate for superconductivity [5], perhaps at temperatures as high as 10 -15 K as for the ...

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Pressure-Induced Superconductivity inCaLi2

Cited by 29 publications

References 19 publications

Novel High Pressure Structures and Superconductivity ofCaLi2

Novel High Pressure Structures and Superconductivity ofCaLi2

High-pressure studies with x-rays using diamond anvil cells

Pressure-induced superconductivity in europium metal

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