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Pressure induced phase transition in metallic LaB6: A Raman study

Muthu, DVS and Jayaraman, A and Chandrabhas, N and Sood, AK and Teredesai, P (1998) Pressure induced phase transition in metallic LaB6: A Raman study. [Book Chapter]

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We report high pressure Raman studies on single crystals of metallic LaB6 upto a pressure of 16.$ GPa. Raman spectra shows three lines at 680 cm(-1) (T-2g), 1120 cm(-1) (E-g) and 1258 cm(-1) (A(1g)), associated with the internal modes of B-6 molecule. The T-2g mode shows an asymmetric Fano line shape, arising from the interference between the phonon line and the electronic continuum. The line is fitted with I(omega) = I-0(q + epsilon(2))/(I + epsilon(2)) where epsilon = (omega - omega(0))/Gamma, omega(0) is the phonon frequency renormalised due to electron-phonon self energy corrections, Tis the width parameter proportional to the square of the matrix element of the electron-phonon interaction potential. The parameter a signifies the strength of interference. Most interestingly our pressure data for the T-2g mode shows a significant change in the slope of the mode frequency with pressure d omega(0)/dP and Gamma at 9.5 GPa. This clearly indicates that LaB6 undergoes a subtle phase transition at 9.5 GPa within the metallic phase.

Item Type: Book Chapter
Series.: Solid State Physics: Proceedings of the D. A. E. Solid State Physics Symposium
Publisher: Universities Press india Ltd
Additional Information: Copyright of this article belongs to Universities Press india Ltd.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 16 Mar 2012 10:33
Last Modified: 16 Mar 2012 10:34
URI: http://eprints.iisc.ac.in/id/eprint/43889

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