Abstract
Abstract
Superconductivity enhancement is often associated with phonon softening by doping or external pressure. In this paper, we report
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1
2
-type trialuminides Al3V as a typical example belonging to this scenario. The electronic, phononic and superconducting properties have been studied by using the first-principle method. Under uniaxial compression, the superconducting transition temperature Tc
of Al3V can be increased from ≈1.5 K to its maximum at ≈7.3 K when the lattice approaches the structural instability. A detailed investigation of Al3V reveals that the (V: d)-(Al: p) hybrid bands are strongly coupled to the phonon modes with lower frequency. The uniaxial compression induces a significant softening of the phonon mode with non-zero phonon line-width, and yet keeps the electron density of states near the Fermi level unchanged. This leads to a stronger electron–phonon coupling (EPC) and therefore a higher Tc
. On the contrary, the
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structure is more stable against the hydrostatic pressure and the phonon energy actually grows up when the hydrostatic pressure is increased. As a result, EPC becomes weaker and Tc
can be reduced to
⩽
0.3 K under high hydrostatic pressure. Our results present an interesting example that superconductivity can enhanced by tuning the softened phonon via pressure or doping.
Funder
National Natural Science Foundation of China
Natural Science Foundation of Shaanxi Province
Subject
Materials Chemistry,Electrical and Electronic Engineering,Metals and Alloys,Condensed Matter Physics,Ceramics and Composites