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Ultrafast Light Switching of Ferromagnetism in EuSe
A B Henriques1, X Gratens1, P A Usachev1
1Instituto de Física, Universidade de São Paulo (USP), 05508-090 São Paulo, Brazil.
Physical Review Letters
|June 9, 2018
Summary
Light induces ferromagnetic behavior in the antiferromagnetic semiconductor EuSe on a picosecond timescale. This photoinduced magnetization arises from giant spin polarons and enhanced magnetic susceptibility.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Optoelectronics
Background:
- Antiferromagnetic semiconductors offer unique electronic and magnetic properties.
- Controlling magnetic alignment in these materials with external stimuli is challenging.
- Europium selenide (EuSe) exhibits competing antiferromagnetic and ferromagnetic interactions.
Purpose of the Study:
- To investigate the effect of light on the magnetic alignment of the antiferromagnetic semiconductor EuSe.
- To elucidate the mechanism behind light-induced magnetization in EuSe.
- To explore the potential for ultrafast optical control of magnetism.
Main Methods:
- Excitation of EuSe with light resonant to its band gap.
- Time-resolved measurements to observe magnetic changes on picosecond timescales.
- Analysis of electron-hole pair generation and spin polaron formation.
Main Results:
- Light resonant with the band gap induced ferromagnetic alignment in EuSe within picoseconds.
- Photoexcitation generated giant spin polarons with magnetic moments up to 6000 Bohr magnetons.
- Increasing light intensity led to full magnetization of the illuminated region.
Conclusions:
- A novel mechanism for large photoinduced magnetization in EuSe was demonstrated.
- The effect is attributed to enhanced magnetic susceptibility in the presence of competing magnetic interactions.
- Ultrafast optical control of magnetism in antiferromagnetic semiconductors is achievable.
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