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Prediction of Nontrivial Band Topology and Superconductivity in Mg2Pb

Guang Bian, Tay-Rong Chang, Angus Huang, Yuwei Li, Horng-Tay Jeng, David J. Singh, Robert J. Cava, Weiwei Xie
(Submitted on 9 Mar 2017)

The interplay of BCS superconductivity and nontrivial band topology is expected to give rise to opportunities for creating topological superconductors, achieved through pairing spin-filtered boundary modes via superconducting proximity effects. The thus-engineered topological superconductivity can, for example, facilitate the search for Majorana fermion quasiparticles in condensed matter systems. Here we report a first-principles study of Mg

2
Pb and predict that it should be a superconducting topological material. The band topology of Mg

2
Pb is identical to that of the archetypal quantum spin Hall insulator HgTe, while isostructural and isoelectronic Mg

2
Sn is topologically trivial; a trivial to topological transition is predicted for Mg

2
Sn

1-x
Pb

x
for x~0.77. We propose that Mg

2
Pb-Mg

2
Sn quantum wells should generate robust spin-filtered edge currents in analogy to HgTe/CdTe quantum wells. In addition, our calculations predict that Mg

2
Pb should become superconducting upon electron doping. Therefore, Mg

2
Pb is expected to provide a practical material platform for studying emergent phenomena arising from the interplay of superconductivity and band topology.

https://arxiv.org/abs/1703.03308