Calculations of the superconducting properties of scandium under high pressure

Nixon, Lane W.; Papaconstantopoulos, D. A.; Mehl, Michael J.

doi:10.1103/physrevb.76.134512

Cited by 17 publications

(12 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A similar observation was reported in the 1990s, with ρ T ( ) largely reasonable but α ν F ( ) 2 exceeding experimental values by a factor 2 or 3 in places [14]. In the current literature the McMillan formula, or a variation of it, is often used in making a rough estimate of T c [15][16][17][18][19][20][21][22]. Sometimes a novel density functional theory of the superconducting state has been attempted [23][24][25][26].…”

Section: Introductionsupporting

confidence: 60%

Empirical rule to reconcile Bardeen–Cooper–Schrieffer theory with electron–phonon interaction in normal state

Zheng

Walmsley

2014

Phys. Scr.

View full text Add to dashboard Cite

We introduce a simple empirical rule wherein the pairing interaction in superconductors is cancelled when normal and umklapp phonon scattering coexist. Superconductivity then arises solely from the residual umklapp contribution. As a result the deduced electron-phonon interactions in niobium, tantalum, lead and aluminum become virtually identical in the normal and superconducting states. Transition temperatures calculated under the rule are accurate within a few per cent when compared with experimental data. Features of the Matthias relations are also explained. The high T c so far predicted for metallic hydrogen is probably overly optimistic.

show abstract

Section: Introductionsupporting

confidence: 60%

Empirical rule to reconcile Bardeen–Cooper–Schrieffer theory with electron–phonon interaction in normal state

Zheng

Walmsley

2014

Phys. Scr.

View full text Add to dashboard Cite

show abstract

“…These trends, where B is roughly proportional to ͗͘, also agree with those from similar investigations into the lighter third column elements of fcc yttrium 34 and fcc scandium. 35 The variations in the density of states at the Fermi level with pressure, and the is maintained above 7 eV/ Å 2 for more than half the pressure range. The electron-phonon coupling increases with pressure, reaching maxima of 1.35 at 8.45 GPa in the LDA and 1.27 at 13.7 GPa in the GGA.…”

Section: E Superconductivitymentioning

confidence: 99%

Electronic structure and superconducting properties of lanthanum

2008

Self Cite

View full text Add to dashboard Cite

The total energy and electronic structure of lanthanum have been calculated in the bcc, fcc, hcp, and double hcp structures for pressures up to 35 GPa. The full-potential linearized-augmented-plane-wave method was used with both the local-density approximation ͑LDA͒ and generalized-gradient approximation ͑GGA͒. The correct phase ordering has been found by the GGA results, with lattice parameters and bulk moduli in good agreement with experimental data. The GGA method shows excellent agreement with experiment while the LDA results show some discrepancies. The calculated strain energies for the fcc and bcc structures demonstrate the respective stable and unstable configurations at ambient conditions. The calculated superconductivity properties under pressure for the fcc structure are also found to agree well with measurements. Both LDA and GGA, with minor differences, reproduce well the experimental results for the superconducting critical temperature T c .

show abstract

“…However, to pinpoint the mechanism(s) responsible for the significant increase in T c with pressure in experiment, detailed electronic structure calculations are needed. Nixon et al [52] recently used an augmented plane wave (APW) method to calculate the electronic structure of Sc assuming, for simplicity, an fcc phase. Over the pressure range 20 to 80 GPa they find that the Hopfield parameter η increases by nearly a factor of four, whereas the electronic density of states N(E f ) decreases by 15%, the Coulomb repulsion µ * decreasing by only 5%.…”

Section: Electronic Structure Calculationsmentioning

confidence: 99%

Comparison of the pressure dependences ofTcin the trivalentd-electron superconductors Sc, Y, La, and Lu up to megabar pressures

2008

View full text Add to dashboard Cite

Whereas dhcp La superconducts at ambient pressure with T c ≃ 5 K, the other trivalent d-electron metals Sc, Y, and Lu only superconduct if high pressures are applied. Earlier measurements of the pressure dependence of T c for Sc and Lu metal are here extended to much higher pressures. Whereas T c for Lu increases monotonically with pressure to 12.4 K at 174 GPa (1.74 Mbar). T c for Sc reaches 19.6 K at 107 GPa, the 2nd highest value observed for any elemental superconductor. At higher pressures a phase transition occurs whereupon T c drops to 8.31 K at 111 GPa. The T c (P ) dependences for Sc and Lu are compared to those of Y and La. An interesting correlation is pointed out between the value of T c and the fractional free volume available to the conduction electrons outside the ion cores, a quantity which is directly related to the number of d electrons in the conduction band.

show abstract

Calculations of the superconducting properties of scandium under high pressure

Cited by 17 publications

References 20 publications

Empirical rule to reconcile Bardeen–Cooper–Schrieffer theory with electron–phonon interaction in normal state

Empirical rule to reconcile Bardeen–Cooper–Schrieffer theory with electron–phonon interaction in normal state

Electronic structure and superconducting properties of lanthanum

Comparison of the pressure dependences ofTcin the trivalentd-electron superconductors Sc, Y, La, and Lu up to megabar pressures

Contact Info

Product

Resources

About