کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5492333 | 1525678 | 2017 | 15 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Phonon dispersion models for MgB2 with application of pressure
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
فیزیک ماده چگال
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چکیده انگلیسی
We evaluate, via the Local Density and the Generalised Gradient Approximations to the Density Functional Theory (DFT), the change in form and extent of the E2g phonon anomaly of MgB2 with increase in applied pressure up to 20 GPa. Ab initio DFT calculations on the phonon dispersion (PD) for MgB2 show a phonon anomaly symmetrically displaced around Î, the reciprocal lattice origin. This anomaly is related to nesting between diametrically opposite sides of tubular elements of Fermi surfaces, which correspond to sigma bonding and run approximately parallel to the Î-A reciprocal space direction. The anomaly is parallel to Î-A and along Î-M and Î-K. The extent of the E2g phonon anomaly, δ, along Î-M and Î-K is a measure of the thermal energy, Tδ, that matches within error the experimental onset superconducting transition temperature, Tc. Ab initio DFT calculations with pressure for â5 GPa < P <â20 GPa show a linear reduction in Tδ that closely matches experimental Tc values for MgB2. For phonon-mediated superconductors with AlB2-type structures, the thermal energy of the phonon anomaly, Tδ, is a reliable predictor of Tc.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physica C: Superconductivity and its Applications - Volume 536, 15 May 2017, Pages 11-17
Journal: Physica C: Superconductivity and its Applications - Volume 536, 15 May 2017, Pages 11-17
نویسندگان
Jose A. Alarco, Peter C. Talbot, Ian D.R. Mackinnon,