Insights into Ultrafast Demagnetization in Pseudogap Half-Metals

Mann A, Walowski J, Muenzenberg M, Maat S, Carey MJ, Childress JR, Mewes C, Ebke D, Drewello V, Reiss G, Thomas A (2012)
Physical Review X 2(4).

Journal Article | Published | English

No fulltext has been uploaded

Author
; ; ; ; ; ; ; ; ; ;
Abstract
Interest in femtosecond demagnetization dynamics was sparked by Bigot's experiment in 1996, which unveiled the elementary mechanisms that relate the electrons' temperature to their spin order. Simultaneously, the application of fast demagnetization experiments has been demonstrated to provide key insight into technologically important systems such as high-spin-polarization metals, and consequently there is broad interest in further understanding the physics of these phenomena. To gain new and relevant insights, we performed ultrafast optical pump-probe experiments to characterize the demagnetization processes of highly spin-polarized magnetic thin films on a femtosecond time scale. Full spin polarization is obtained in half-metallic ferro- or ferrimagnets, where only one spin channel is populated at the Fermi level, whereas the other one exhibits a gap. In these materials, the spin-scattering processes is controlled via the electronic structure, and thus their ultrafast demagnetization is solely related to the spin polarization via a Fermi golden-rule model. Accordingly, a long demagnetization time correlates with a high spin polarization due to the suppression of the spin-flip scattering at around the Fermi level. Here we show that isoelectronic Heusler compounds (Co2MnSi, Co2MnGe, and Co2FeAl) exhibit a degree of spin polarization between 59% and 86%. We explain this behavior by considering the robustness of the gap against structural disorder. Moreover, we observe that CoFe-based pseudogap materials, such as partially ordered Co-Fe-Ge and Co-Fe-B alloys, can reach similar values of the spin polarization. By using the unique features of these metals we vary the number of possible spin-flip channels, which allows us to pinpoint and control the half-metals' electronic structure and its influence on the elementary mechanisms of ultrafast demagnetization.
Publishing Year
ISSN
eISSN
PUB-ID

Cite this

Mann A, Walowski J, Muenzenberg M, et al. Insights into Ultrafast Demagnetization in Pseudogap Half-Metals. Physical Review X. 2012;2(4).
Mann, A., Walowski, J., Muenzenberg, M., Maat, S., Carey, M. J., Childress, J. R., Mewes, C., et al. (2012). Insights into Ultrafast Demagnetization in Pseudogap Half-Metals. Physical Review X, 2(4).
Mann, A., Walowski, J., Muenzenberg, M., Maat, S., Carey, M. J., Childress, J. R., Mewes, C., Ebke, D., Drewello, V., Reiss, G., et al. (2012). Insights into Ultrafast Demagnetization in Pseudogap Half-Metals. Physical Review X 2.
Mann, A., et al., 2012. Insights into Ultrafast Demagnetization in Pseudogap Half-Metals. Physical Review X, 2(4).
A. Mann, et al., “Insights into Ultrafast Demagnetization in Pseudogap Half-Metals”, Physical Review X, vol. 2, 2012.
Mann, A., Walowski, J., Muenzenberg, M., Maat, S., Carey, M.J., Childress, J.R., Mewes, C., Ebke, D., Drewello, V., Reiss, G., Thomas, A.: Insights into Ultrafast Demagnetization in Pseudogap Half-Metals. Physical Review X. 2, (2012).
Mann, Andreas, Walowski, Jakob, Muenzenberg, Markus, Maat, Stefan, Carey, Matthew J., Childress, Jeffrey R., Mewes, Claudia, Ebke, Daniel, Drewello, Volker, Reiss, Günter, and Thomas, Andy. “Insights into Ultrafast Demagnetization in Pseudogap Half-Metals”. Physical Review X 2.4 (2012).
This data publication is cited in the following publications:
This publication cites the following data publications:

Export

0 Marked Publications

Open Data PUB

Web of Science

View record in Web of Science®

Sources

arXiv 1202.3874

Search this title in

Google Scholar