basics
Examples
Given a crystalline material, its Brillouin torus is the space of distinguishable momenta/wave vectors of its electronic excitations. Due to the periodicity of the crystal, also these momenta/wave vectors are (dually) periodically identified, which makes this space an n-torus.
Mathematically, the discrete space underlying a crystal is a subset of a Euclidean space (the set of atomic sites) which is preserved (as a subset) by the action of a crystallographic group , where is a full lattice (and the corresponding point group). Then its Brillouin torus is the Pontrjagin dual group of this lattice (eg. Freed-Moore 13):
The concept is named after:
Textbooks on solid state physics traditionally speak of the “reciprocal lattice” (e.g. Kittel 1953, p. 27) which is the dual lattice , e.g.:
Michael Reed, Barry Simon, p. 311 of: Sec. XIII.16 Schrödinger operators with periodic potentials, of: Methods of Modern Mathematical Physics – IV: Analysis of Operators, Academic Press (1978)
David Tong, §2.2.2 in: Lectures on solid state physics (2017) pdf, webpage
The resulting Brillouin torus is often left implicit. It is made explicit for instance in:
Daniel Freed, Gregory Moore, p. 52 of: Twisted equivariant matter, Ann. Henri Poincaré (2013) 14: 1927 [arXiv:1208.5055, doi:10.1007/s00023-013-0236-x]
Guo Chuan Thiang, §2.1 in: Topological Semimetals, Encyclopedia of Mathematical Physics 2nd ed (2024) [arXiv:2407.12692]
Kiyonori Gomi, Guo Chuan Thiang, p. 9 in: Crystallographic T-duality, J. Geom. Phys 139 (2019) 50-77 [doi:10.1016/j.geomphys.2019.01.002, arXiv:1806.11385]
Texts that make explicit the choice of spin structure on Brillouin tori:
Ümit Ertem: Weyl semimetals and cobordism [arXiv:2003.04082]
Andy Knoll, Carsten Timm: Irreducible momentum-space spin structure of Weyl semimetals and its signatures in Friedel oscillations, Phys. Rev. B 109 (2024) 035145 [doi:10.1103/PhysRevB.109.035145]
Last revised on June 26, 2025 at 07:07:57. See the history of this page for a list of all contributions to it.