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arXiv · 0909.0594

Strong phonon softening without Fermi surface nesting

D. Lamago·M. Hoesch·M. Krisch·R. Heid·K. -P. Bohnen·P. Boeni·D. Reznik
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Abstract

Interactions with electronic excitations can soften and/or broaden phonons. They are greatly amplified at wavevectors Q+- that connect parallel (nested) sheets of the Fermi surface. In such a case, called a Kohn anomaly, the phonon dispersion sharply dips and its linewidth has a maximum at Q+-. Here we present results of inelastic x-ray scattering measurements that uncovered soft phonons in chromium far from Q+-. They appear in addition to the previously reported soft phonons at Q+-. Calculations in the local density approximation (LDA) show that the new anomalies originate from enhanced electron-phonon coupling. A similar mechanism may explain phonon anomalies away from nesting wavevectors in copper oxide superconductors and other compounds.

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D. Lamago, M. Hoesch, M. Krisch, R. Heid, K. -P. Bohnen, P. Boeni, D. Reznik. 2009-09-03. Strong phonon softening without Fermi surface nesting. https://arxiv.org/abs/0909.0594

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