HIGH RESOLUTION COMPTON SCATTERING AS PROBE OF FERMIOLOGY AND ELECTRON CORRELATIONS. A. Bansil, Physics Dept., Northeastern Univ., Boston MA 02115, USA

In 1993, the I. U. Cryst. Commission on Charge, Spin, and Momentum Densities started a new project, "Fermiology of High-Tc Superconductors via High Resolution Synchrotron-based Compton Scattering Spectroscopy". Properly timed to exploit the rapid world-wide development of high resolution spectrometers, this project has generated vigorous activity. A substantial progress has been made in delineating the nature of electron states in simpler systems which serve as the foundation for understanding complex materials. Feasibility of determining Fermi surface radii via high resolution Compton has been demonstrated.^[1] Careful comparisons between the measured and computed spectra in Li, Be, and LiMg^[1-3] clearly reveal departures from the conventional one-particle local density approximation (LDA) picture of the ground state momentum density of the electron gas; work on a variety of other systems is in progress. Reconstruction of the full 3D density from a series of Compton profiles in Li is beginning to yield direct insight for the first time into the size of the momentum density break at the Fermi momentum in a metal.^[3] Much work has been carried out by a number of groups in standardizing data handling procedures for synchrotron-based Compton data using Si as a target material. This talk provides an overview of the relevant work completed to date, and outlines areas of further study likely to prove fruitful in establishing high resolution Compton as a tool for investigating Fermiology related issues in wide range of materials.

[1] Y. Sakurai, et al., Phys. Rev. Letters 74, 2252(1995).

[2] K. Hamalainen, et al., Phys. Rev. B (1996).

[3] W. Schulke et al. (preprint).