Superconductivity in Lithium Under Pressure

Jishi, Radi A.; Benkraouda, Maamar; Bragin, J.

doi:10.1007/s10909-007-9340-y

Cited by 6 publications

(5 citation statements)

References 25 publications

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“…The above result means that the depairing electron correlations in calcium are relatively strong (the classical low-temperature superconductors µ * C is about 0.1 [25]). It can be noted that similar non-standard value of µ * C has been obtained for lithium and CaLi 2 [26], [27], [28], [29], [30]. For example, the properties of the superconducting state in the fcc phase of lithium for the pressure values 22.3 GPa (T C = 7.27 K) and 29.7 GPa (T C = 13.93 K) have been specified in the paper [29].…”

Section: The Coulomb Pseudopotentialsupporting

confidence: 77%

Characterization of the high‐pressure superconductivity in the Pnma phase of calcium

Szczȩśniak

Szczęśniak

2012

Physica Status Solidi (b)

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The thermodynamic parameters of the superconducting state in calcium under the pressure at 161 GPa have been calculated within the framework of the Eliashberg approach. It has been shown that the value of the Coulomb pseudopotential is high (µ * C = 0.24) and the critical temperature (TC = 25 K) should be determined from the modified Allen-Dynes formula. In addition, it has been found that the basic dimensionless ratios of the thermodynamic parameters significantly diverge from the BCS predictions, and take the following values: (i) The zero temperature energy gap to the critical temperature (R1 ≡ 2∆ (0) /kBTC) is equal to 4.01. (ii) The ratio R2 ≡ C S (TC ) − C N (TC) /C N (TC ) equals 2.17, where C S and C N denote the specific heats for the superconducting and normal state, respectively. (iii) The quantity R3 ≡ TCC N (TC ) /H 2 C (0) = 0.158, where HC indicates the thermodynamic critical field. Finally, it has been proven that the electron effective mass is large and takes the maximum of 2.32me at TC.

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Section: The Coulomb Pseudopotentialsupporting

confidence: 77%

Characterization of the high‐pressure superconductivity in the Pnma phase of calcium

Szczȩśniak

Szczęśniak

2012

Physica Status Solidi (b)

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“…Lithium has been known to exhibit superconductivity with T c 10 K under high pressure. [52][53][54][55] Early ab initio calculations [56][57][58][59][60] including that based on the SCDFT 61 reproduced the experimentally observed pressure dependence of T c quantitatively. However, a later sophisticated calculation 62 using the Wannier interpolation technique 63 has shown that the numerically converged electron-phonon coupling coefficient is far smaller than the previously reported values.…”

Section: Application To Lithium Under Pressuresmentioning

confidence: 99%

“…Instead of using the Wannier-interpolation technique, we carried out the Fermi surface integration for the input Eliashberg functions 3 with broad smearing functions, 43 and we obtained λ consistent with the latest calculation, 62 which is smaller than the earlier estimates. [56][57][58][59][60][61] The material and pressure dependence of the theoretical T c follows that of λ. With K=K ph , T c is estimated to be of order of 10K.…”

Section: Calculation With Small N Pmentioning

confidence: 99%

Density Functional Theory for Plasmon-Assisted Superconductivity

Akashi

Arita

2014

J. Phys. Soc. Jpn.

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We review the recent progress in the density functional theory for superconductors (SCDFT). Motivated by the long-studied plasmon mechanism of superconductivity, we have constructed an exchange-correlation kernel entering the SCDFT gap equation which includes the plasmon effect. For the case of lithium under high pressures, we show that the plasmon effect substantially enhances the transition temperature (Tc) by cooperating with the conventional phonon mechanism and results in a better agreement between the theoretical and experimentally observed Tc. Our present formalism will be a first step to density functional theory for unconventional superconductors.Comment: 9 pages, 7 figures; accepted for publication in J. Phys. Soc. Jpn. Special Topics; conference proceedings of The International Conference on Strongly Correlated Electron Systems (SCES) 201

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“…15 There have been extensive theoretical studies of superconductivity in the fcc phase of Li under pressure. 26,[28][29][30][31][32][33][34][35][36][37] In particular, it has been suggested that superconductivity in fcc Li is driven by Fermi-surface nesting 30,31 and Kohn anomalies, 30 resulting in an unusually high T c . On the other hand, no theoretical investigation has been made on superconductivity of the high-pressure cI16 phase based on firstprinciples calculation of the phonon spectra and the electronphonon spectral function.…”

Section: B High Pressure Fcc\ Ci16 Transitionmentioning

confidence: 99%

“…Theoretical works on pressure-induced superconductivity so far, however, have focused on the fcc phase only. [26][27][28][29][30][31][32][33][34][35][36][37] The only exception is the study on fcc and cI16 by Christensen and Novikov 26 based on a rigid muffintin approximation-which proved to be inadequate for Li ͑Ref. 34͒-and without calculation of the phonon spectra for cI16.…”

Section: Introductionmentioning

confidence: 99%

Superconductivity in lithium under high pressure investigated with density functional and Eliashberg theory

et al. 2009

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Structural phase transitions and superconducting properties in three phases ͑9R, fcc, and cI16͒ of solid Li are investigated using a pseudopotential plane-wave method based on density functional perturbation theory. In particular, it is shown that phonon softening is responsible for a pressure-induced fcc→ cI16 transition as well as for a significant enhancement of electron-phonon coupling and superconducting transition temperature T c preceding this structural transformation. The nature of superconductivity in the fcc and cI16 phases is examined by solving the Eliashberg equations with the spectral function ␣ 2 F͑͒ obtained from first-principles calculations and by evaluating the functional derivative ␦T c / ␦␣ 2 F͑͒. The calculated T c reaches a maximum at pressure close to the fcc→ cI16 transition and is significantly reduced in the cI16 phase, in agreement with the trend observed experimentally. The variation in T c as a function of pressure is explained in terms of the functional derivative and shifts of the spectral weight.

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Superconductivity in Lithium Under Pressure

Cited by 6 publications

References 25 publications

Characterization of the high‐pressure superconductivity in the Pnma phase of calcium

Characterization of the high‐pressure superconductivity in the Pnma phase of calcium

Density Functional Theory for Plasmon-Assisted Superconductivity

Superconductivity in lithium under high pressure investigated with density functional and Eliashberg theory

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