2001/06/29 by Izumi Hase, Kunihiko Yamaji
Materials Science · Physics and Astronomy · #Boron and Carbon Nanomaterials Research #Physics of Superconductivity and Magnetism #Superconductivity in MgB2 and Alloys #cond-mat.supr-con
paper · pdf · doi:10.1143/jpsj.70.2376
15 pages, 7 graphs. to be published in J. Phys. Soc. Jpn. 70_, No.8
arxiv created 2001/06/29 · openalex publication_date 2001/08/15 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
First principle FLAPW band calculations of the new superconductor MgB2 were performed and the polarization function P12(Q) between the two p-bands mainly formed of boron pz-orbital was calculated. We found that P12(Q) is substantially enhanced around Q=(0,0,p/c), which supports the two-band mechanism of superconductivity for MgB2. P12(Q) peaks at Qz ~ 0.3(2p/c) and Qz \~ 0.5(2p/c). These two peaks are related to the nesting of these Fermi surfaces, but significantly deviates from the position expected from the simplest tight-binding bands for the p-bands. From the calculations for different lattice parameters, we have found significant dependences on the isotopic species of B and on the pressure effect of the polarization function in accordance with the respective changes of Tc in the above-mentioned framework.