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arXiv · 1607.04178

Presence of Exotic Electronic Surface States in LaBi and LaSb

X. H. Niu·D. F. Xu·Y. H. Bai·Q. Song·X. P. Shen·B. P. Xie·Z. Sun·Y. B. Huang·D. C. Peets·D. L. Feng
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Abstract

Extremely high magnetoresistance (XMR) in the lanthanum monopnictides La$X$ ($X$ = Sb, Bi) has recently attracted interest in these compounds as candidate topological materials. However, their perfect electron-hole compensation provides an alternative explanation, so the possible role of topological surface states requires verification through direct observation. Our angle-resolved photoemission spectroscopy (ARPES) data reveal multiple Dirac-like surface states near the Fermi level in both materials. Intriguingly, we have observed circular dichroism in both surface and near-surface bulk bands. Thus the spin-orbit coupling-induced orbital and spin angular momentum textures may provide a mechanism to forbid backscattering in zero field, suggesting that surface and near-surface bulk bands may contribute strongly to XMR in La$X$. The extremely simple rock salt structure of these materials and the ease with which high-quality crystals can be prepared suggests that they may be an ideal platform for further investigation of topological matter.

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X. H. Niu, D. F. Xu, Y. H. Bai, Q. Song, X. P. Shen, B. P. Xie, Z. Sun, Y. B. Huang, D. C. Peets, D. L. Feng. 2016-11-01. Presence of Exotic Electronic Surface States in LaBi and LaSb. https://doi.org/10.1103/physrevb.94.165163

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