Dresden 2006 – scientific programme
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TT: Tiefe Temperaturen
TT 7: Superconductivity & Solids At Low Temperature - Poster Session
TT 7.5: Poster
Monday, March 27, 2006, 14:00–17:45, P1
First-Principles Electronic Structure Study of Layered TB2C2 Compounds (T = Y, La, Lu) — •Alim Ormeci and Helge Rosner — MPI for Chemical Physics of Solids, Dresden, Germany
Metal borocarbides TB2C2, where T = Y and rare earth (R) metals, are layered compounds with metal atom layers alternating with the (B2C2) layers. The RB2C2 compounds crystallize in the tetragonal LaB2C2-type structure with symmetry P4/mbm (SG 127). CaB2C2 also has the same crystal structure and is isoelectronic to MgB2. However, due to heteropolar B-C bonds it is an insulator. The compound YB2C2, on the other hand, is a metal and a superconductor. Although there are some ambiguities about its crystal structure [1], it can be regarded as an electron-doped version of CaB2C2. Consequently, both the crystal and electronic structure of YB2C2, as well as the electron-phonon interactions in the (B2C2) layers are of interest.
We use the FPLO method to investigate the above mentioned aspects in YB2C2. In particular, we find that YB2C2 has the LaB2C2-type structure in agreement with the FP-LAPW results [1]. Furthermore, we study the effects of (i) possible disorder in the B-C network, and (ii) different stacking orders on the electronic properties. LaB2C2 and LuB2C2 are included in the study for comparative reasons.
[1] S. Khmelevskyi, et al. Supercond. Sci. Technol. 18 422 (2005)