Enhanced superconductivity in the high pressure phase of SnAs studied from first principles
| Autor: | G. Vaitheeswaran, P. V. Sreenivasa Reddy, Tom Millichamp, Stephen B Dugdale, V. Kanchana |
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| Rok vydání: | 2017 |
| Předmět: |
Physics
Superconductivity Phase transition Condensed matter physics Phonon Fermi surface 02 engineering and technology Electronic structure 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Electronic Optical and Magnetic Materials Phase (matter) 0103 physical sciences Condensed Matter::Strongly Correlated Electrons Density functional theory Electrical and Electronic Engineering 010306 general physics 0210 nano-technology Generalised susceptibility Phase diagram |
| Zdroj: | Reddy, P V S, Kanchana, V, Millichamp, T E, Vaitheeswaran, G & Dugdale, S B 2017, ' Enhanced superconductivity in the high pressure phase of SnAs studied from first principles ', Physica B: Condensed Matter, vol. 505, pp. 33-40 . https://doi.org/10.1016/j.physb.2016.10.026 |
| ISSN: | 0921-4526 |
| DOI: | 10.1016/j.physb.2016.10.026 |
| Popis: | First principles calculations are performed using density functional theory and density functional perturbation theory for SnAs. Total energy calculations show the first order phase transition from an NaCl structure to a CsCl one at around 37 GPa, which is also confirmed from enthalpy calculations and agrees well with experimental work. Calculations of the phonon structure and hence the electron-phonon coupling, λ ep , and superconducting transition temperature, T c , across the phase diagram are performed. These calculations give an ambient pressure T c , in the NaCl structure, of 3.08 K, in good agreement with experiment whilst at the transition pressure, in the CsCl structure, a drastically increased value of T c = 12.2 K is found. Calculations also show a dramatic increase in the electronic density of states at this pressure. The lowest energy acoustic phonon branch in each structure also demonstrates some softening effects. Electronic structure calculations of the Fermi surface in both phases are presented for the first time as well as further calculations of the generalised susceptibility with the inclusion of matrix elements. These calculations indicate that the softening is not derived from Fermi surface nesting and it is concluded to be due to a wavevector-dependent enhancement of the electron-phonon coupling. |
| Databáze: | OpenAIRE |
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