Photo-induced ferromagnetism i Photo-induced ferromagnetism i bulk-Cd bulk-Cd 0.95 0.95 Mn Mn 0.05 0.05 Te via exciton Te via exciton Y. Hashimoto, H. Mino, T. Yamamuro, D. Kanbara, A T. Matsusue, B S. Takeyama Graduate School of Science and Technology, Chiba University, Chiba, Japan A Faculty of Engineering, Chiba University, Chiba, Japan B The institute for Solid State Physics, University of Tokyo, Chiba, Japan magnetic polarons magnetic polarons
Photo-induced ferromagnetism in. Y. Hashimoto, H. Mino, T. Yamamuro, D. Kanbara, A T. Matsusue, B S. Takeyama Graduate School of Science and Technology, Chiba University, Chiba, Japan A Faculty of Engineering, Chiba University, Chiba, Japan - PowerPoint PPT Presentation
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Photo-induced ferromagnetism inPhoto-induced ferromagnetism in
bulk-Cdbulk-Cd0.950.95MnMn0.050.05Te via excitonTe via exciton
Y. Hashimoto, H. Mino, T. Yamamuro, D. Kanbara, AT. Matsusue, BS. TakeyamaGraduate School of Science and Technology, Chiba University, Chiba, Japan
AFaculty of Engineering, Chiba University, Chiba, JapanBThe institute for Solid State Physics, University of Tokyo, Chiba, Japan
magnetic polaronsmagnetic polarons
Magnetic polarons
Mn spin
Exciton spine
h
e
h
E
Free Exciton Magnetic Polaron (FEMP)
Bound Magnetic Polaron (BMP)
Localization only by sp-d exchange interaction
A Golnic, et. al. J. Phys. C16, 6073 (1983)M. Umehara, Phys. Rev. B 68, 193202 (2003)
Local magnetic order surrounding an impurity bound exciton
What is interesting about FEMP ?
Photo-induced magnetismvia the FEMP
Circular polarized light
FEMP
BMP
No magnetism via the BMP
Circular polarized light
Dark exciton magnetic polarons
Transient absorption with circularly polarized pump and probe pulses.
T [
a. u
.]
20151050
Time delay [ps]
() ( )
Hole spin relaxation
Exciton spin relaxation
Individual spin relaxation of the
electron and hole
Dark exciton may form dark exciton magnetic polaron
via the strong p-d exchange interaction
Dark exciton formation
1
G
2 21
e
h
Hole spin flip < 1 ps
Free exciton magnetic polaron (FEMP) in CdMnTe
High quality CdMnTe sample
with low Mn concentration
CW and time-resolved Photoluminescence
Time- and spectral-resolved
photo-induced Faraday rotation
(TR- and SR-PIFR)
Current work :
Alloy potential fluctuation : Small
x = 5 ~ 10% → FEMP energy : Large
S. Takeyama, J. of Crys. Growth, 184-185 (1998) 917-920
Mn Concentration [%]
Localiza
tion
en
erg
y
105
Alloy Potential fluctuation
Localization energy of Magnetic Polaron
Sample
Bulk-Cd1-xMnxTe x = 5% GaAs substrate
Cd1-yMgyTe
Quartz disk
The opaque GaAs substrate was removed.
CdMgTe layer is transparent in the wavelength of CdMnTe’s resonance.