Link between Weyl-fermion chirality and spin texture

Assessing Nontrivial Topology in Weyl Semimetals by Dichroic Photoemission

“…In close comparison to theory, ARPES signatures, such as dichroism, yield detailed information about the character of the initial Bloch states near the Weyl points, e.g., with regard to surface or bulk localization and orbital symmetry. These findings will be also relevant to other material classes, such as MoTe 2 and WTe 2 where the Weyl character of the band structure remains controversial [12,20,[35][36][37]. More generally, our results push forward the general understanding of dichroic ARPES and its relation to orbital angular momentum and Berry curvature.…”

“…The topology in Weyl semimetals (WSMs) manifests itself in the monopole charge of the Berry curvature, i.e., the integral of the latter around a WP is integer quantized reflecting a Chern number of AE1. Substantial progress in identifying Berry flux monopoles has been made, e.g., using transport experiments [8] or circular dichroism (CD) [9][10][11][12][13] that indicate characteristic spectral weight behavior in surface and bulk states near WPs. However, the ARPES related signatures rely on simplifying assumptions such as twoband systems or a free-electron (FE) like final state in CD [10].…”

Low-energy spin-polarized electrons: their role in surface physics

“…The data can then be plotted as I (k , k z ), whereby k denotes the parallel wave vector in the k x , k y plane, i.e., resulting into intensity maps along the K − Γ − K (Figure 4E) and along the M − Γ − M (Figure 4F) lines in the surface Brillouin zones. These data then permit a direct comparison to band structures, with the dark blue lines marking the calculated bulk electronic states [36].…”

“…Spin-resolved momentum microscopy data recorded for NiTe 2 exhibit a clear spin-polarization of the surface Dirac cones. (a full discussion of the spin-resolved data from this system a subject to a forthcoming publication [36]).…”