First-Principle Study of Phonons and "Goniopolarity" in Electron Transport in ReBe2 and MnBe2

ReBe2 and MnBe2 are both transition metal-beryllium compounds, with the same crystal symmetry. We used density functional theory (DFT) to study the electron and phonon properties of these two materials. We calculated phononic properties with phonopy, utilizing the finite difference method. We study the electron transport properties using BoltzTraP2, computing the Seebeck and Hall coefficients. This reveals that ReBe2 displays a property known as “goniopolarity”[1] - that is, along one direction, it displays electron type transport, and along another, it displays hole type transport.

[1] He, B., Wang, Y., Arguilla, M.Q. et al. The Fermi surface geometrical origin of axis-dependent conduction polarity in layered materials. Nat. Mater. 18, 568–572 (2019). https://doi.org/10.1038/s41563-019-0309-4