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Magnetic dichroism from optically excited quantum well states
Cheng-Tien Chiang1, Aimo Winkelmann, Ping Yu
1Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle(Saale), Germany.
Physical Review Letters
|October 2, 2009
Summary
We observed magnetic dichroism in optically excited states using two-photon photoemission. This effect in cobalt films is linked to quantum well states and spin-orbit coupling.
Area of Science:
- Surface science
- Quantum mechanics
- Magnetism
Background:
- Two-photon photoemission is a technique to study electronic states.
- Magnetic dichroism provides information about magnetic properties.
- Ultrathin magnetic films exhibit unique quantum phenomena.
Purpose of the Study:
- To demonstrate magnetic dichroism from optically excited states.
- To investigate unoccupied quantum well states in cobalt films.
- To elucidate the origin of circular and linear magnetic dichroism.
Main Methods:
- Utilizing two-photon photoemission spectroscopy.
- Growing ultrathin cobalt films on a Cu(001) substrate.
- Performing measurements under magnetization reversal.
Main Results:
- Observed unoccupied quantum well states in cobalt films.
- Detected a sizable intensity change in photoemission upon magnetization reversal.
- Simultaneously compared circular and linear magnetic dichroism.
Conclusions:
- The observed magnetic dichroism originates from intermediate quantum well states.
- Spin-orbit coupling is identified as a key factor in the observed effects.
- Fundamental symmetry requirements for magnetic dichroism were verified.
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