Emergence of topological electronic phases in elemental lithium under pressure

Abstract

Lithium, a prototypical simple metal under ambient conditions, has a surprisingly rich phase diagram under pressure, taking up several structures with reduced symmetry, low coordination numbers, and even semiconducting character with increasing density. Using first-principles calculations, we demonstrate that some predicted high-pressure phases of elemental Li also host topological electronic structures. Beginning at 80 GPa and coincident with a transition to the Pbca phase, we find Li to be a Dirac nodal line semimetal. We further calculate that Li retains linearly-dispersive energy bands in subsequent predicted higher pressure phases, and that it exhibits a Lifshitz transition between two Cmca phases at 220 GPa. The Fd-3m phase at 500 GPa forms buckled honeycomb layers that give rise to a Dirac crossing 1 eV below the Fermi energy. The well-isolated topological nodes near the Fermi level in these phases result from increasing p-orbital character with density at the Fermi level, itself a consequence of rising 1s core wavefunction overlap, and a preference for nonsymmorphic symmetries in the crystal structures favored at these pressures. Our results provide evidence that under pressure, bulk 3D materials with light elements, or even pure elemental systems, can undergo topological phase transitions hosting nontrivial topological properties near the Fermi level with measurable consequences; and that, through pressure, we can access these novel phases in elemental lithium.

5 pages, 5 figures, accepted for publication

References in corpus (7)

• The electronic properties of graphene
• Observation of the Wigner-Huntington Transition to Solid Metallic Hydrogen
• Computing topological invariants without inversion symmetry
• Z2Pack: Numerical Implementation of Hybrid Wannier Centers for Identifying Topological Materials
• Velocity Renormalization and Carrier Lifetime in Graphene from Electron-Phonon Interaction
• Interstitial Electronic Localization
• High-pressure lithium as an elemental topological semimetal

Cited by in corpus (3)

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