Study on Momentum Density and Fermi Surface in Paramagnetic Cr and W by Positron Annihilation

The three‐dimensional electron‐positron momentum densities in paramagnetic Cr and W are reconstructed from measurements of two‐dimensional angular correlation of positron annihilation radiations (2D‐ACAR) by the image reconstruction technique based on a direct Fourier transformation. The experimental momentum density for paramagnetic Cr and W shows the contribution of the Fermi surface sheets; the electron surface at Γ, the hole surface at H, the hole surface at N. The Fermi surface topology obtained from the present results agrees with the theory and other experiments.