Electronic topological and structural transitions in AuGa(2) under pressure
Alka B Garg1, Ashok K Verma, V Vijayakumar
1High Pressure Physics Division, Purnima Laboratories, Bhabha Atomic Research Centre, Mumbai 400085, India.
Summary
This study reveals that a flat band near the Fermi level causes AuGa(2)
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid-State Physics
Background:
- AuGa(2) exhibits anomalous physical properties under pressure.
- Understanding these anomalies is crucial for materials science applications.
Purpose of the Study:
- To investigate the anomalous behavior of AuGa(2) under pressure.
- To elucidate the underlying electronic and structural mechanisms.
Main Methods:
- First-principles electronic band structure calculations.
- High-pressure electrical resistance and thermoelectric power (TEP) measurements.
- Synchrotron-based high-pressure x-ray diffraction.
Main Results:
- A flat band near the Fermi level along the Γ-X direction is identified as the cause of anomalous behavior.
- AuGa(2) undergoes a structural phase transition above 7 GPa.
- An electronic topological transition (ETT) is observed near 3.2 GPa, evidenced by TEP and P-V data.
- The high-pressure phase (above 7 GPa) is a distortion of the CaF(2) phase, evolving continuously with pressure.
Conclusions:
- The electronic band structure, particularly the flat band, dictates the unusual properties of AuGa(2).
- Pressure-induced electronic topological transitions and structural phase transitions are key to understanding AuGa(2)'s behavior.
- The material exhibits complex phase evolution under high pressure.
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