Magnetic circular dichroism in x-ray absorption and core-level photoemission of Fe/Cu(001)
- Lawrence Livermore National Lab., CA (United States)
- Naval Res., Lab., Washington, DC (United States)
We report the first observation of magnetic circular dichroism in both x-ray absorption and core-level photoemission of ultra thin magnetic films using circularly polarized x-rays. Iron films (1--4 ML) grown on a Cu(001,) substrate at 150 K and magnetized perpendicular to the surface show dramatic changes in the L{sub 2,3} branching ratio for different x-ray polarizations. For linearly-polarized x-rays perpendicular to the magnetic axis of the sample the branching ratio was 0.75. For films {ge} 2 ML, this ratio varied from 0.64 to 0.85 for photon spin parallel and anti-parallel, respectively, to the magnetic axis. This effect was observed either by changing the x-ray helcity for a fixed magnetic axis, or by reversing the magnetic axis for a fixed x-ray helicity. Our observation can be analyzed within a simple one-electron picture, if the raw branching ratios are normalized so that the linear value becomes statistical. Furthermore, warming the films to {approximately} 300 K eliminated this effect, indicating a loss of magnetization in the film over a temperature range of {approximately} 30 K. Finally, reversing the relative orientation of the photon spin and the magnetic axis from parallel to anti-parallel allowed measurement of the exchange splitting of the Fe 2p core levels which was found to be {approximately} 0.2 eV. These results are consistent with earlier studies, but the use of off-plane circularly-polarized x-rays from a bending magnet monochromator offers {approximately} 2 orders of magnitude greater intensity than typical spin-polarization measurements.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10186402
- Report Number(s):
- UCRL-JC--108837; CONF-920735--4; ON: DE93001305
- Country of Publication:
- United States
- Language:
- English
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