### Abstract

The thermodynamic parameters of the superconducting state in calcium under the pressure of 161GPa 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 (T_{C}=25K) 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 (R_{1}≡ 2Δ(0)/k_{B}T_{C}) is equal to 4.01. (ii) The ratio R_{2}≡ (C^{S}(T_{C}) equals 2.17, where C^{S}and C^{N}denote the specific heats for the superconducting and normal states, respectively. (iii) The quantity R_{3}≡T_{C}C^{N}(T_{C})/H^{2} _{C}(0)=0.158, where H_{C}indicates the thermodynamic critical field. Finally, it has been proven that the electron effective mass is large and takes the maximum of 2.32m_{e}at T_{C}.

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

Pages (from-to) | 2194-2201 |

Number of pages | 8 |

Journal | Physica Status Solidi (B) Basic Research |

Volume | 249 |

Issue number | 11 |

DOIs | |

Publication status | Published - 2012 |

Externally published | Yes |

### Fingerprint

### Keywords

- Ca Pnma phase
- High-pressure effects
- Superconductivity
- Thermodynamic properties

### ASJC Scopus subject areas

- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials

### Cite this

*Physica Status Solidi (B) Basic Research*,

*249*(11), 2194-2201. https://doi.org/10.1002/pssb.201248032

**Characterization of the high-pressure superconductivity in the Pnma phase of calcium.** / Szczesniak, R.; Szczesniak, D.

Research output: Contribution to journal › Article

*Physica Status Solidi (B) Basic Research*, vol. 249, no. 11, pp. 2194-2201. https://doi.org/10.1002/pssb.201248032

}

TY - JOUR

T1 - Characterization of the high-pressure superconductivity in the Pnma phase of calcium

AU - Szczesniak, R.

AU - Szczesniak, D.

PY - 2012

Y1 - 2012

N2 - The thermodynamic parameters of the superconducting state in calcium under the pressure of 161GPa 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=25K) 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≡ 2Δ(0)/kBTC) is equal to 4.01. (ii) The ratio R2≡ (CS(TC) equals 2.17, where CSand CNdenote the specific heats for the superconducting and normal states, respectively. (iii) The quantity R3≡TCCN(TC)/H2 C(0)=0.158, where HCindicates the thermodynamic critical field. Finally, it has been proven that the electron effective mass is large and takes the maximum of 2.32meat TC.

AB - The thermodynamic parameters of the superconducting state in calcium under the pressure of 161GPa 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=25K) 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≡ 2Δ(0)/kBTC) is equal to 4.01. (ii) The ratio R2≡ (CS(TC) equals 2.17, where CSand CNdenote the specific heats for the superconducting and normal states, respectively. (iii) The quantity R3≡TCCN(TC)/H2 C(0)=0.158, where HCindicates the thermodynamic critical field. Finally, it has been proven that the electron effective mass is large and takes the maximum of 2.32meat TC.

KW - Ca Pnma phase

KW - High-pressure effects

KW - Superconductivity

KW - Thermodynamic properties

UR - http://www.scopus.com/inward/record.url?scp=84868672313&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84868672313&partnerID=8YFLogxK

U2 - 10.1002/pssb.201248032

DO - 10.1002/pssb.201248032

M3 - Article

VL - 249

SP - 2194

EP - 2201

JO - Physica Status Solidi (B): Basic Research

JF - Physica Status Solidi (B): Basic Research

SN - 0370-1972

IS - 11

ER -