Experimental determination of the state-dependent enhancement of the electron-positron momentum density in solids

摘要

The state dependence of the enhancement of the electron-positron momentum density is investigated for some transition and simple metals (Cr, V, Ag, and Al). Quantitative comparison with linearized muffin-tin orbital calculations of the corresponding quantity in the first Brillouin zone is shown to yield a measurement of the enhancement of the s, p, and d states, independent of any parametrizations in terms of the unscreened electron density local to the positron. An empirical correction that can be applied to a first-principles state-dependent model is proposed that reproduces the measured state dependence very well, yielding a general model for the enhancement of the momentum distribution of positron annihilation measurements, including those of angular correlation and coincidence Doppler broadening techniques.%J. Laverock;T. D. Haynes;M. A. Alam;S. B. Dugdale;