Ultraviolet–visible magnetic circular dichroism spectroscopy and its application of magnetic materials
Hua Shu, Hsu1*
1Department of Applied Physics, National Pingtung University, Pingtung, Taiwan
* presenting author:Hua Shu Hsu, email:hshsu@mail.nptu.edu.tw
Energy dependent magnetic circular dichroism (MCD) spectra, from which the difference between the absorptions of left and right circularly polarized light at specific energies can be identified, can give valuable information of the spin polarized density of states of materials. For example, element-selective X-ray MCD has been used to clarify the origin of the ferromagnetism. In contrast to x-ray spectroscopy, ultraviolet–visible (2 eV–6 eV) MCD spectroscopy has also been considered as a powerful tool especially for studying the spin-polarized band structures of a semiconductor between its conduction band and the valence band.
This talk will address some examples:
1. Analyses of UV-vis MCD spectra of ferromagnetic C:ZnO semiconductors[1]:
Room temperature ferromagnetism (RTFM) was observed in a C:ZnO system. The anhysteretic magnetization curves of C:ZnO reveals a defect-mediated ferromagnetic behavior. The appearance of a narrow ferromagnetic MCD peak can be attributed to the origin of the observed RTFM.
2. A sizeable interfacial MCD effect of Co/C composites[2]:
A strong MCD effect is observed in Co/C composites. The MCD peak is closed to an absorption edge at the σ-σ* gap transition. Our results provide evidence that the sizeable magneto-optical effects are contributed by the hybridization effect at the Co/C interface.
An overview of the basic MCD ideas underlying this research and several applications will also be presented.

[1] H. S. Hsu, Y. Tung, Y. J. Chen, M. G. Chen, J. S. Lee, and S. J. Sun, Phys. Status Solidi RRL 5, No. 12, 447 (2011).
[2] H. S. Hsu, P. E. Liu, C. W. Chang, S. J. Sun, C. H. Lee, H. C. Su, Y. Y. Chin, H. J. Lin, C. T. Chen and M. J. Huang, Carbon, 77, 398(2014).

Keywords: MCD, ZnO, Carbon