High-pressure anomaly in the normal state of MgB2

Modak, P. ; Verma, A. K. ; Gaitonde, D. M. ; Rao, R. S. ; Godwal, B. K. (2004) High-pressure anomaly in the normal state of MgB2 Physical Review B, 70 (18). 184506_1-184506_5. ISSN 0163-1829

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Official URL: http://prb.aps.org/abstract/PRB/v70/i18/e184506

Related URL: http://dx.doi.org/10.1103/PhysRevB.70.184506


The E2g mode phonon frequency anomaly, observed in high-pressure Raman measurements for the high-temperature superconductor MgB2 and conjectured to arise due to a phonon-assisted electronic topological transition (ETT), has been corroborated by us with the details of electronic structure calculations of this compound. The present studies have been carried out with a B-atom displacement of the frozen-in E2g-mode phonon that mimics the effects of thermal vibrations. We found a splitting of the doubly degenerate σ band along the Γ-A direction. The splitting of the band reduces with pressure, causing an ETT at 18 GPa. This ETT is expected to cause anomaly in the E2g phonon mode by influencing the ionic system. Our calculated electron-phonon coupling constant λ , for the distorted lattice with a frozen-in displacement, also depicts an anomalous variation around 18 GPa.

Item Type:Article
Source:Copyright of this article belongs to American Physical Society.
ID Code:11632
Deposited On:13 Nov 2010 14:08
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