|Abstract||Unlike time-reversal topological insulators, surface metallic states with Dirac cone dispersion in the recently discovered topological crystalline insulators (TCIs) are protected by crystal symmetry. To date, TCI behaviors have been observed in SnTe and the related alloys Pb1-xSnx Se/Te, which incorporate heavy elements with large spin-orbit coupling (SOC). Here, by combining first-principles and ab initio tight-binding calculations, we report the formation of a TCI in relatively lighter rocksalt SnS and SnSe. This TCI is characterized by an even number of Dirac cones at the high-symmetry (001), (110), and (111) surfaces, which are protected by the reflection symmetry with respect to the ((1) over bar 10) mirror plane. We find that both SnS and SnSe have an intrinsically inverted band structure even without the SOC and the SOC is necessary only to open the bulk band gap. The bulk band gap evolution upon volume expansion reveals a topological transition from an ambient pressure TCI to a topologically trivial insulator. Our results indicate that the SOC alone is not sufficient to drive the topological transition.|
; li, dianzhong
; li, yiyi
; chen, xing-qiu] chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china. [sun, yan
; shirakawa, tomonori
; yunoki, seiji] riken, computat condensed matter phys lab, wako, saitama 3510198, japan. [sun, yan
; franchini, cesare] univ vienna, fac phys, a-1090 vienna, austria. [zhong, zhicheng] vienna univ technol, inst solid state phys, a-1040 vienna, austria. [shirakawa, tomonori
; yunoki, seiji] japan sci & technol agcy jst, crest, kawaguchi, saitama 3320012, japan. [shirakawa, tomonori
; yunoki, seiji] riken adv inst computat sci aics, computat mat sci res team, kobe, hyogo 6500047, japan. [yunoki, seiji] riken ctr emergent matter sci cems, computat quantum matter res team, wako, saitama 3510198, japan.
; chen, xq (reprint author), chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china.
Y. Sun,Z. C. Zhong,T. Shirakawa,et al. Rocksalt SnS and SnSe: Native topological crystalline insulators[J]. Physical Review B,2013,88(23).