Issue 38, 2019

Pressure induced semiconductor–semimetal–superconductor transition of magnesium hexaborides

Abstract

A thorough structural exploration was performed for MgB6 combining the global structure searching method with first-principles calculations. Besides the known Cmcm phase, new phases, i.e. I4/mmm, C2/m-I, C2/m-II and P21/m, were predicted to be stable in the pressure range of 18–100 GPa. Unexpectedly, Cmcm-MgB6 was found to be a semiconductor with an indirect band gap of 0.38 eV with the HSE06 functional, in good agreement with the experimental finding. I4/mmm-MgB6 stabilized above 18 GPa exhibits semimetallic behaviour with a topological node-line near the Fermi level. Consequently, C2/m-I MgB6 with a sandwich structure similar to MgB2 is predicted to be a superconductor with a critical temperature (Tc) of 9.5 K. By analysing the electronic structure, the intriguing semiconductor–semimetal–superconductor transition may be ascribed to the delocalization of more B-p electrons in the boron sublattice. The novel functions uncovered for MgB6 may inspire more efforts to discover materials with intriguing properties.

Graphical abstract: Pressure induced semiconductor–semimetal–superconductor transition of magnesium hexaborides

Supplementary files

Article information

Article type
Paper
Submitted
07 Jul 2019
Accepted
17 Aug 2019
First published
19 Aug 2019

Dalton Trans., 2019,48, 14299-14305

Pressure induced semiconductor–semimetal–superconductor transition of magnesium hexaborides

L. Duan, J. Su, N. Gong, B. Wan, P. Chen, P. Zhou, Z. Wang, Z. Li and L. Wu, Dalton Trans., 2019, 48, 14299 DOI: 10.1039/C9DT02813G

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