IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI+TF-ThA

Paper MI+TF-ThA3
Occupied and Unoccupied Metallic Quantum Well States in the Cu/fccM/Cu(100) [M=Ni, Fe] System

Thursday, November 1, 2001, 2:40 pm, Room 110

Session: Magnetic Thin Films and Surfaces I
Presenter: A.G. Danese, Rutgers University
Authors: A.G. Danese, Rutgers University
R.A. Bartynski, Rutgers University
D.A. Arena, Lawrence Livermore National Lab & Lawrence Berkeley Lab
M. Hochstrasser, Lawrence Livermore National Lab & Lawrence Berkeley Lab
J.G. Tobin, Lawrence Livermore National Lab & Lawrence Berkeley Lab
Correspondent: Click to Email
Multilayers of alternating magnetic (FM) and non magnetic (NM) layers have attracted a great deal of attention due to their technological importance. We have studied the Metallic Quantum Well (MQW) electronic structure of the prototypical NM/FM/NM systems, Cu/fccM/Cu(100) [M=Ni,Fe], using both angle resolved photoemission (PE) and inverse photoemission (IPE) along the Gamma-bar X-bar direction. We have also used a phase accumulation model (PAM) to calculate the dispersions of MQW electronic states along this axis. The PAM predicts that MQW states will have a high effective mass when they lie in the energy and momentum region of the projected spin polarized band gap of the underlying FM material. PE of the Cu/fccNi/Cu(100) system shows one high effective mass state inside the Ni band gap and another near the gap edge while IPE shows one just above the Ni gap, in good qualitative agreement with the PAM. Numerous MQW states were seen using IPE on Cu/fccFe/Cu(100) but no pronounced high-effective-mass state was seen in the Fe band gap. We believe this can be explained if the Fe film is actually NM which will move the location of the high effective mass states from where they are expected. The PAM also predicts that MQW states will increase in energy as a function of increasing Cu thickness. Although we observed this in our IPE results for MQW states in Cu/fccFe/Cu(100) and PE of Cu/fccNi/Cu(100), our IPE data for Cu/fccNi/Cu(100) show MQW states decreasing in energy with increasing Cu thickness. This same result was observed for Cu films on a Ni(100) single crystal and attributed to lattice mismatch between Cu and Ni, but we have shown that strain cannot account for the behavior of these MQW states and are currently studying how the interface roughness between the Cu and Ni film may provide an explanation. We will discuss our results in the context of the PAM and address the origins of discrepancies between the PAM's predictions and our measurements.