Publication Details

Li, W., Li, Y., Chen, R., Zeng, R., Dou, S. X., Zhu, M. & Jin, H. (2008). Raman study of element doping effects on the superconductivity of MgB2. Physical Review B (Condensed Matter and Materials Physics), 77 (9), 094517-1-094517-7.


The influences of phonon frequency and unit cell volume on the superconductivity of element-doped MgB2 are discussed with reference to a Raman study on SiC, C, Mn, and Al-Ag-doped Mg-B materials. A phenomenon has been found in the doped samples, in that the phonon frequency changes to counteract the crystal lattice variation to keep the system stable within a Grüneisen parameter of 2.0–4.0. The chemical doping effects on phonon frequency and unit cell volume can be explained by the harmonicity-anharmonicity competition in the compounds. A decreased electronic density of states is responsible for the depression of superconductivity that is seen in doped MgB2. The possibility of a high critical temperature, Tc, in the Mg-B system exists if the material can possess both a high phonon frequency and a big unit cell volume at the same time, as indicated by the isotope effect and hydrogenation experiments.

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