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Abstract

The quasi-one-dimensional superconductor ${\mathrm{V}}_{2}{\mathrm{Ga}}_{5}$, with the superconducting transition temperature ${T}_{c}\ensuremath{\sim}3.6\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, has recently been proposed to be an intermetallic topological material, although the experimental evidence for its nontrivial band topology is still lacking. Here, we report on its electrical and thermoelectric transport properties, as well as on its quantum de Haas-van Alphen (dHvA) oscillations. At low temperatures, ${\mathrm{V}}_{2}{\mathrm{Ga}}_{5}$ shows a linear-in-$B$ magnetoresistance, a scaling typically seen in many topological materials. Its thermoelectric power shows a pronounced two-peak profile, one centered around 70 K and the other one at $\ensuremath{\sim}10$ K, while the Nernst coefficient exhibits a significant enhancement in the same temperature range. Quantum dHvA oscillations reveal a single frequency, with a nontrivial Berry phase close to $\ensuremath{\pi}$, associated with the putative topological carriers in its $\ensuremath{\alpha}$ pocket. Finally, the superconductivity is found to be linearly suppressed by physical pressure, with the upper critical field ${H}_{c2}$ consistent with the two-gap superconductivity in this topological superconductor candidate. Our results provide the direct experimental evidence for the existence of topological carriers in this quasi-one-dimensional superconductor.

Transport and quantum oscillations in the quasi-one-dimensional superconductor V2Ga5

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Abstract

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