J. J. Paggel

Angle-resolved photoemission from atomic-layer-resolved quantum well states in Ag/Fe(100)

Abstract Angle-resolved photoemission from thin films of Ag on Fe(100) grown with a low temperature deposition and annealing technique shows clear quantum well peaks for coverages up to 12 monolayers. Pairs of peaks are sometimes observed in the spectra; atomic layer resolution is demonstrated and used to explain these pairs without invoking spin splitting. The peaks are observed only within an energy window defined by the minority spin hybridization gap within the Fe substrate. Large intensity variations of the quantum well states with photon energy are observed.

Quantum well photoemission from atomically uniform Ag films : determination of electronic band structure and quasi-particle lifetime in Ag(100)

Photoemission from atomically uniform layers of Ag on a Fe(100) substrate is employed for the determination of the bulk electronic band structure of Ag. The high degree of control of the layer thickness allows the interferometric measurement of the electron momentum normal to the sample surface. This leads to an unprecedented precision in the electronic band structure determined from the experiment. The high quality of the layers also allows the discussion of the line shape of the quantum well peaks for the first time and gives access to the intrinsic and extrinsic broadening parameters of the line shape.

Quantum-well photoemission spectroscopy of atomically-uniform films

Abstract Using a low-temperature growth technique and an Fe whisker sample, atomically-uniform films of Ag on Fe(100) are prepared. Extremely sharp quantum-well peaks are obtained in these films, as peak broadening from thickness variation is eliminated. The quality of the spectra allows the observation of quantum-well peaks in films over 100 monolayers thick. Quantum-well peaks from both the sp and d states have been observed and used to map the associated bands. The elimination of broadening from thickness variation allows for the interpretation of the peak linewidths in terms of the quasiparticle lifetime and interfacial reflectivity, and the phonon contribution can be deduced from the temperature dependence of the spectra.