Figure 1: Crystal structure of LnPtBi and cleavage surface measured by ARPES.
From: Observation of unusual topological surface states in half-Heusler compounds LnPtBi (Ln=Lu, Y)
(a) Crystal structure of half-Heusler alloy LnPtBi crystal shows a composite of zinc-blend and rocksalt lattices. (b) Unit cell of LnPtBi at the (111) cleavage surface shows the stacking of triangular Ln, Pt and Bi layers. a0 is the in-plane lattice constant of the (111) surface unit cell. (c) Bulk BZ of LnPtBi with high symmetry points labelled. Arrows and shaded surfaces indicate the projection to [100], [010] and [001] directions. (d) Surface BZ in the [111] direction with the high symmetry points labelled. (e) Core level photoemission spectrum on LuPtBi (111) and (001) surfaces clearly shows the characteristic Lu 4f and Bi 5d doublets. These spectra are measured with 75 and 215 eV photons, respectively. (f) Broad FS map of LuPtBi covering five BZs, confirming the shape and size of the surface BZ (overlaid yellow hexagons) on the (111) cleave plane. The uneven intensity of the FS at different BZs results from the matrix element effect.
