Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 10: Focused Session: Frontiers of Electronic Structure Theory 1 (jointly with HL and O)

TT 10.5: Talk

Monday, March 11, 2013, 11:45–12:00, H36

The stability of Bi-Sb-Te layered structures: a first-principles study — •Kirsten Govaerts¹, Marcel H.F. Sluiter², Bart Partoens³, and Dirk Lamoen¹ — ¹EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium — ²Department of Materials Science and Engineering, 3mE, Delft University of Technology, Mekelweg 2, 2628 CD, Delft, The Netherlands — ³CMT group, Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium

Using an effective one-dimensional cluster expansion in combination with first-principles electronic structure calculations we have studied the energetics and electronic properties of Bi-Sb-Te layered systems. Our modified, quintuple based cluster expansion explicitly accounts for the Bi and Sb bilayer formation which is due to a Peierls instability. With this new method, groundstates of Bi-Sb-Te can be found without making the dataset of ab initio calculated structures unreasonably large. Groundstates are found within the binary alloys X-Te, with X corresponding to Bi or Sb, for a Te concentration between 0 and 60 at.%. They form an almost continuous series of (meta)stable structures consisting of consecutive X bilayers next to consecutive X₂Te₃ units. Another binary groundstate is the BiSb structure, consisting of alternating Bi and Sb layers, again forming pairs. Groundstates of ternary compounds all consist of consecutive units of Bi₂Te₃, Sb₂Te₃ and TeSbTeBiTe.