### Abstract

The thermodynamic properties of the high-pressure superconducting phase in CaLi _{2} have been studied. A pressure value of 45 GPa has been chosen, at which the critical temperature reaches the maximum (T _{C} = 12.9 K). The following results have been obtained. (i) The critical temperature cannot be calculated using the classical analytical formulas (McMillan or Allen-Dynes). (ii) The critical value of the Coulomb pseudopotential is high: μ ^{*} _{C} = 0.23. Generalizing the results, the function μ ^{*} _{C} (p) has a high value (μ ^{*} _{C} (p) > 0. 15) in practically the entire pressure range from 28 to 60 GPa. (iii) The remaining fundamental thermodynamic parameters differ from the Bardeen, Cooper, and Schrieffer (BCS) values. In particular, the zero-temperature energy gap to the critical temperature: R _{1} ≡ 2Δ (0)/k _{B}T _{C} = 3.95; the ratio of the specific heat for superconducting (C ^{S}) and the normal (C ^{N}) state: R _{2} ≡ (C ^{S} (T _{C}) - C ^{N} (T _{C})/C ^{N} (T _{C}) = 2.01; and the parameter connected with the zero-temperature thermodynamic critical field: R _{3} = T _{C}C ^{N} (T _{C})/H _{C} ^{2} (0) = 0.158. Finally, it has been shown that the value of the electronic effective mass is high: m ^{*}/m _{e} > 2.

Original language | English |
---|---|

Pages (from-to) | 779-783 |

Number of pages | 5 |

Journal | Solid State Communications |

Volume | 152 |

Issue number | 9 |

DOIs | |

Publication status | Published - May 2012 |

Externally published | Yes |

### Fingerprint

### Keywords

- Cali -superconductor
- High-pressure effects
- Thermodynamic properties

### ASJC Scopus subject areas

- Condensed Matter Physics
- Chemistry(all)
- Materials Chemistry

### Cite this

_{2}at 45 GPa.

*Solid State Communications*,

*152*(9), 779-783. https://doi.org/10.1016/j.ssc.2012.01.045

**Thermodynamic investigations of high-pressure superconducting state in CaLi _{2} at 45 GPa.** / Szczȩśniak, R.; Szczȩśniak, D.

Research output: Contribution to journal › Article

_{2}at 45 GPa',

*Solid State Communications*, vol. 152, no. 9, pp. 779-783. https://doi.org/10.1016/j.ssc.2012.01.045

_{2}at 45 GPa. Solid State Communications. 2012 May;152(9):779-783. https://doi.org/10.1016/j.ssc.2012.01.045

}

TY - JOUR

T1 - Thermodynamic investigations of high-pressure superconducting state in CaLi 2 at 45 GPa

AU - Szczȩśniak, R.

AU - Szczȩśniak, D.

PY - 2012/5

Y1 - 2012/5

N2 - The thermodynamic properties of the high-pressure superconducting phase in CaLi 2 have been studied. A pressure value of 45 GPa has been chosen, at which the critical temperature reaches the maximum (T C = 12.9 K). The following results have been obtained. (i) The critical temperature cannot be calculated using the classical analytical formulas (McMillan or Allen-Dynes). (ii) The critical value of the Coulomb pseudopotential is high: μ * C = 0.23. Generalizing the results, the function μ * C (p) has a high value (μ * C (p) > 0. 15) in practically the entire pressure range from 28 to 60 GPa. (iii) The remaining fundamental thermodynamic parameters differ from the Bardeen, Cooper, and Schrieffer (BCS) values. In particular, the zero-temperature energy gap to the critical temperature: R 1 ≡ 2Δ (0)/k BT C = 3.95; the ratio of the specific heat for superconducting (C S) and the normal (C N) state: R 2 ≡ (C S (T C) - C N (T C)/C N (T C) = 2.01; and the parameter connected with the zero-temperature thermodynamic critical field: R 3 = T CC N (T C)/H C 2 (0) = 0.158. Finally, it has been shown that the value of the electronic effective mass is high: m */m e > 2.

AB - The thermodynamic properties of the high-pressure superconducting phase in CaLi 2 have been studied. A pressure value of 45 GPa has been chosen, at which the critical temperature reaches the maximum (T C = 12.9 K). The following results have been obtained. (i) The critical temperature cannot be calculated using the classical analytical formulas (McMillan or Allen-Dynes). (ii) The critical value of the Coulomb pseudopotential is high: μ * C = 0.23. Generalizing the results, the function μ * C (p) has a high value (μ * C (p) > 0. 15) in practically the entire pressure range from 28 to 60 GPa. (iii) The remaining fundamental thermodynamic parameters differ from the Bardeen, Cooper, and Schrieffer (BCS) values. In particular, the zero-temperature energy gap to the critical temperature: R 1 ≡ 2Δ (0)/k BT C = 3.95; the ratio of the specific heat for superconducting (C S) and the normal (C N) state: R 2 ≡ (C S (T C) - C N (T C)/C N (T C) = 2.01; and the parameter connected with the zero-temperature thermodynamic critical field: R 3 = T CC N (T C)/H C 2 (0) = 0.158. Finally, it has been shown that the value of the electronic effective mass is high: m */m e > 2.

KW - Cali -superconductor

KW - High-pressure effects

KW - Thermodynamic properties

UR - http://www.scopus.com/inward/record.url?scp=84859790645&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84859790645&partnerID=8YFLogxK

U2 - 10.1016/j.ssc.2012.01.045

DO - 10.1016/j.ssc.2012.01.045

M3 - Article

VL - 152

SP - 779

EP - 783

JO - Solid State Communications

JF - Solid State Communications

SN - 0038-1098

IS - 9

ER -