Abstract
We have measured electron-positron momentum density in ${(\mathrm{TMTSF})}_{2}{\mathrm{ClO}}_{4}$ by the positron two-dimensional angular correlation of annihilation radiation (2D-ACAR) technique. Significant anisotropies are found in the momentum density reflecting the low dimensionality of the material. Ab initio plane-wave pseudopotential calculations have been also made to simulate the 2D-ACAR spectra. The calculated 2D-ACAR spectra are in good agreement with the experimental ones. In order to investigate the Fermi-surface structure, we constructed Lock-Crisp-West (LCW) remapped spectra. The resultant spectra show small steps at the expected Fermi-surface position for both the experiment and the calculation. The magnitude of the steps in the experimental LCW spectrum is one third of the calculated one but still one order of magnitude higher than the experimental detection limit. Although we cannot conclude the existence of an ideal Fermi surface due to the finite experimental resolution, we have confirmed, in the experiment, a structure corresponding to the calculated Fermi break.
Published Version
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