Study on the Electron-Positron Momentum Density and Fermi Surface in Hf Using the 2D-ACAR Experiment

Abstract

Electron momentum space density and Fermi surface of Hf were studied using two-dimensional angular correlation of annihilation radiation (2D-ACAR) experimental set-up. From the measured data, three-dimensional momentum space density ρ(P) was calculated, using the reconstruction technique based on Fourier transform. The strong d-like signal and its effect on the Fermi surface features were studied and interpreted in view of the electronic structure of Hf. The Fermi radius was obtained from the locus |∇ρ(P)|max, and it was found to deviate strongly from the free electron one. In the wave vector space, Fermi surface of Hf was constructed using LCW folding procedure, restrained within first Brillouin zone. In addition, its sheets were compared with two band structure calculations using relativistic augmented plane wave (RAPW) method and linear combination of atomic orbital (LCAO) method. Agreements and variations were obtained with the theoretical works.