Strong enhancement of superconductivity in the topological transition metal silicide W5Si3 by Re doping
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Abstract
We report the effect of Re doping in the prototype transition metal silicide W5Si3. Structural analysis shows that Re can substitute up to 20% of W in W5Si3 and its incorporation leads to an anisotropic shrinkage of the tetragonal lattice. Tc of W5−xRexSi3 is strongly enhanced with increasing Re content x from 2.45 K (x = 0) to 6.36 K (x = 1) and higher that of isostructural Mo5−xRexSi3 with the same valence electron count. This Tc enhancement is accompanied by a drastic increase in the upper critical field and attributed to the enhancement of electron–phonon coupling caused by doping-induced phonon softening. Theoretical calculations suggest that the electronic structure of undoped W5Si3 is characterized by strong Z2 invariants (1;000) and this topological character is presumably preserved upon Re doping. Our study indicates that chemical doping provides a facile way to optimize superconductivity in topological transition metal silicides.
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