Termination-dependent topological surface states of the natural superlattice phase Bi_4Se_3
We describe the topological surface states of Bi_4Se_3, a compound in the infinitely adaptive Bi_2-Bi_2Se_3 natural superlattice phase series, determined by a combination of experimental and theoretical methods. Two observable cleavage surfaces, terminating at Bi or Se, are characterized by angle-resolved photoelectron spectroscopy and scanning tunneling microscopy, and modeled by ab initio density functional theory calculations. Topological surface states are observed on both surfaces, but with markedly different dispersions and Kramers point energies. Bi_4Se_3 therefore represents the only known compound with different topological states on differently terminated, easily distinguished and stable surfaces.
Additional Information© 2013 American Physical Society. Received 18 April 2013; published 30 August 2013. The authors acknowledge helpful discussions with B. A. Bernevig and F. Chen. The financial support of the National Science foundation, Grants No. NSF-DMR-0819860 and No. NSF-DMR-1104612, DARPA-SPAWAR Grant No. N6601-11-1-4110, and the ARO MURI program, Grant No. W911NF-12-1-0461, are gratefully acknowledged. The work at Brookhaven was carried out in part at the Center for Functional Nanomaterials and the National Synchrotron Light Source which are supported by the US Department of Energy (DOE), Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. The Advanced Light Source is supported by the US DOE, Office of Basic Energy Sciences, under Contract No.DE-AC02-05CH11231. One of the authors (S.N.-P.) acknowledges support of European Community through the Marie-Curie OEF fellowship.
Published - PhysRevB.88.081108.pdf
Submitted - 1305.3558v3.pdf