2020/09/30 by Sonu Verma, Arijit Kundu, Tarun Kanti Ghosh
Chemistry · Physics and Astronomy · #Atomic physics #Chemistry #Condensed matter physics #Dispersion relation #Electron #Fermi Gamma-ray Space Telescope #Fermi energy #Fermi gas #Fermi level #Fermi surface #Long wavelength limit #Magnetic properties of thin films #Physics #Physics of Superconductivity and Magnetism #Plasmon #Polarization (electrochemistry) #Quantum and electron transport phenomena #Quantum mechanics #Random phase approximation #Surface plasmon #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.102.195208
published as Physical Review B 102, 195208 (2020) · 18 pages, 9 figures
openalex publication_date 2020/11/30 · arxiv created 2020/12/04 · arxiv updated 2020/12/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study the dynamical polarization function and plasmon modes for spin-orbit coupled noncentrosymmetric metals such as Li2(Pd_1\ensuremath-xPtx)3B. These systems have different Fermi surface topologies for Fermi energies above and below the spin degenerate point, which is also known as the band touching point (BTP). We calculate the exact dynamical polarization function numerically and also provide its analytical expression in the long wavelength limit. We obtain the plasmon dispersion within the framework of random phase approximation. In noncentrosymmetric metals, there is a finite energy gap in between intra- and interband particle-hole continuum for vanishing excitation wave vector. In the long wavelength limit, the width of the interband particle-hole continuum behaves differently for Fermi energies below and above the BTP as a clear signature of the Fermi surface topology change. We find a single undamped optical plasmon mode lying in between the intra- and interband particle-hole continuum for Fermi energies above and below the BTP within a range of parameters. The plasmon mode below the BTP has smaller velocity than that of above the BTP. It is interesting to find that as we tune the Fermi energy around the BTP, the plasmon mode becomes damped within a range of electron-electron interaction strengths. For Fermi energies above and below the BTP, we also obtain an approximate analytical result of plasma frequency and plasmon dispersion which match well with their numerical counterparts in the long wavelength limit. The plasmon dispersion is \ensuremath∝q2 with q being the wave vector for plasmon excitation in the long wavelength limit. We find that varying the carrier density with fixed electron-electron interaction strength or vice versa does not change the number of undamped plasmon modes, although damped plasmon modes can be more in number for some values of these parameters. We demonstrate our results by calculating the loss function and optical conductivity, which can be measured in experiments.