Department of Physics, University of California, Berkeley
Materials Sciences Division, Lawrence Berkeley National Lab
A New Analyzer for Spin Photoemission Experiments
In our laboratory we have developed a novel analyzer for Spin-ARPES experiments (see photo at right). This analyzer employs a new concept for spin detection, based on a Time-of-Flight analyzer (which is 10 times more efficient than dispersive analyzers) coupled with a high-efficiency spin detector utilizing exchange scattering (about 50-100 times more efficient for spin detection than using spin-orbit interaction as in Mott detectors).
Spin-ARPES is the only experimental tool that can directly probe the spin-resolved bandstructure of materials. Our “Spin-TOF” system allows us to perform experiments with energy resolution, momentum resolution, and collection efficiency unprecedented for a Spin-ARPES system. It has been used at the Advanced Light Source for measurements in wide energy and momentum ranges and with with the tabletop laser in our laboratory for high resolution measurements. -->
The high efficiency of data collection allows for experimental scope never before possible with spin resolution. For example, the spin-TOF system mapped the spin-dependence of the bandstructure of Au(111) surface states, shown at right. These data, which would take prohibitively long to accumulate on most spin-ARPES systems, were taken in just two hours.
The Spin-TOF system collects data rapidly enough to test a wide range of experimental parameters such as sample temperature or photon polarization. It can be a crucial probe for understanding topological insulators (see here), Rashba systems, and magnetic materials.
A high-efficiency spin-resolved photoemission spectrometer combining time-of-flight spectroscopy with exchange-scattering polarimetry
C. Jozwiak, J. Graf, G. Lebedev, N. Andresen, A. K. Schmid, A. V. Fedorov, F. El Gabaly, W. Wan, A. Lanzara, and Z. Hussain
Rev. Sci. Instrum. 81, 053904 (2010).
High-Efficiency Spin-Resolved Photoemission Spectrometer IB-2695
Christopher Jozwiak, Alessandra Lanzara, Nord Andresen, Zahid Hussain, Andreas Schmid, Jeff Graf, and Gennadi Lebedev