The partial substitution of Al for Mg in the MgB2 superconductor produces both a progressive reduction of its superconducting transition temperature T-c and the occurrence of two distinct structural phases at low and high Al content, as shown by X-ray diffraction data. To achieve a deeper understanding of the effect of the Al content, we investigated the x dependence of the Raman phonon spectrum in Mg1-xAlxB2 compounds. We analyze the evolution of the E-2g Raman-active phonon mode observed on increasing x both in our measurements (0 less than or equal to x less than or equal to 0.5) and in recent experiments (0 less than or equal to x less than or equal to 1). Our analysis shows the connection between the evolution with x of the E-2g phonon and the T-c suppression, thus supporting the hypothesis that superconductivity in MgB2 is mediated by a strong e-ph coupling with the E-2g Mode. We then derive the electron-phonon coupling constant lambda in the 0-0.5 x range.

EFFECTS OF THE Al CONTENT IN MgB2: A RAMAN STUDY / Dore, Paolo; Postorino, Paolo; A., Congeduti; Nucara, Alessandro; Bianconi, Antonio; Di Castro, Daniele; S., De Negri; A., Saccone. - In: INTERNATIONAL JOURNAL OF MODERN PHYSICS B. - ISSN 0217-9792. - 17:4-6(2003), pp. 505-511. [10.1142/S0217979203016157]

EFFECTS OF THE Al CONTENT IN MgB2: A RAMAN STUDY

DORE, Paolo;POSTORINO, Paolo;NUCARA, Alessandro;BIANCONI, Antonio;DI CASTRO, Daniele;
2003

Abstract

The partial substitution of Al for Mg in the MgB2 superconductor produces both a progressive reduction of its superconducting transition temperature T-c and the occurrence of two distinct structural phases at low and high Al content, as shown by X-ray diffraction data. To achieve a deeper understanding of the effect of the Al content, we investigated the x dependence of the Raman phonon spectrum in Mg1-xAlxB2 compounds. We analyze the evolution of the E-2g Raman-active phonon mode observed on increasing x both in our measurements (0 less than or equal to x less than or equal to 0.5) and in recent experiments (0 less than or equal to x less than or equal to 1). Our analysis shows the connection between the evolution with x of the E-2g phonon and the T-c suppression, thus supporting the hypothesis that superconductivity in MgB2 is mediated by a strong e-ph coupling with the E-2g Mode. We then derive the electron-phonon coupling constant lambda in the 0-0.5 x range.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11573/252882
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