Electronic topological and structural transitions in AuGa2 under pressure

Garg, Alka B. ; Verma, Ashok K. ; Vijayakumar, V. ; Rao, R. S. ; Godwal, B. K. (2006) Electronic topological and structural transitions in AuGa2 under pressure Journal of Physics: Condensed Matter, 18 (37). pp. 8523-8532. ISSN 0953-8984

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Official URL: http://iopscience.iop.org/0953-8984/18/37/010

Related URL: http://dx.doi.org/10.1088/0953-8984/18/37/010


Results of electronic band structure calculations, electrical resistance, thermoelectric power (TEP), and x-ray diffraction measurements, under pressure carried out on AuGa2 to investigate its anomalous behaviour are reported. The first principles electronic band structure calculations confirm that a flat band close to the Fermi level along the Γ-X direction of the Brillouin zone is responsible for the unusual behaviour of AuGa2. In synchrotron-based high-pressure x-ray diffraction measurements, it is observed to undergo a structural phase transition above 7 GPa. The TEP variation with pressure and the P-V data up to 7 GPa transformed to the universal equation of state (UEOS) indicate the existence of an electronic topological transition (ETT) near 3.2 GPa. Consistent with this, in electronic structure calculations carried out at reduced sample volume corresponding to 4 GPa, it is seen that the flat band crosses the Fermi level. The structure above 7 GPa is a distortion of the CaF2 phase. This structure continuously evolves with increasing pressure. The continuous variation of electrical resistance across the transition is consistent with this.

Item Type:Article
Source:Copyright of this article belongs to Institute of Physics Publishing.
ID Code:11943
Deposited On:13 Nov 2010 13:31
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