MgB2 and AlB2 at high pressures |
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Authors: | I Loa K Kunc K Syassen |
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Institution: | Max-Planck-Institut für Festk?rperforschung , Heisenbergstr. 1, Stuttgart , D-70569 , Germany |
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Abstract: | We have studied the effect of pressure on vibrational and electronic properties of MgB2 and AlB2 by ab initio calculations and Raman spectroscopy. The comparison between the calculations and the Raman data puts the common assignment of a broad spectral feature near 600 cm?1 in MgB2 to the E 2g phonon into question. At variance with MgB2 the Raman spectra of AlB2 exhibit a well-defined E 2g mode indicating that the anomalous Raman spectrum encountered in MgB2 is not related to the metallicity of the samples nor is it intrinsic to crystals of the AlB2 structure type. A theoretical estimate of the pressure dependence of T c in MgB2 shows that the experimentally observed decrease of T c under pressure is predominantly due to phonon frequency shifts. |
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Keywords: | Mgb2 Alb2 Superconductivity Lattice Dynamics Raman Spectroscopy High Pressure |
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