June 19, 2024: The research group reports on an efficient orbital terahertz source in Advanced Materials

Recently, the research group, again in collaboration with Professor Albert Fert and Professor Henri-Yves Jaffres from Paris-Saclay University, has achieved significant advancements in the field of orbital electronics. The team proposed a novel approach to generate orbital currents using a CoPt alloy, designing a CoPt/Cu/MgO structure to characterize the orbital generation, and observed strong orbital terahertz emission through femtosecond laser excitation experiments. This work paves the way for the development of efficient orbital terahertz radiation sources. On June 19, 2024, the related research results were published online in Advanced Materials under the title “Efficient Orbitronic Terahertz Emission Based on CoPt Alloy.” Recent studies have indicated that orbital currents can be excited in ferromagnets (such as Ni) and converted into ultrafast charge currents through orbital-charge conversion. However, the terahertz emission efficiency based on Ni materials is still much lower than that of spin-based terahertz radiation sources. In response, the research team proposed the novel idea of using a CoPt alloy to generate orbital currents and experimentally observed strong orbital terahertz emission in the CoPt/Cu/MgO structure. The team also creatively proposed a scheme that combines orbital and spin contributions, achieving further breakthroughs in terahertz emission performance.

March 6, 2024: The research group reports on light-induced orbital currents in the Ni system in Nature Communications

Recently, the research group, in collaboration with Professor Albert Fert and Professor Henri-Yves Jaffres from Paris-Saclay University, has made significant progress in the field of orbital electronics. The team proposed a new experimental method for generating and emitting terahertz radiation based on light-induced orbital currents, discovering ultrafast orbital currents induced by light in a Ni/NM/MgO multilayer film system. The experiments measured the velocity of orbital carriers and the orbital decoherence time. This work opens new avenues for the development of next-generation integrated circuit devices. On March 6, 2024, the related research results were published online in Nature Communications under the title “Orbitronics: light-induced orbital currents in Ni studied by terahertz emission experiments.” Recent studies have shown that currents can form orbital currents through the orbital Hall effect or the orbital Rashba-Edelstein effect, and can exert torque on magnetization, thus forming orbital moments. According to the Onsager reciprocal relations, the inverse effects of the orbital Hall effect or the orbital Rashba-Edelstein effect can convert orbital currents into charge currents. The research team detected light-induced orbital-charge conversion in the Ni/NM/MgO multilayer film using terahertz spectroscopy, and through analysis of the impact of Cu on the terahertz emission spectrum in the Ni/Cu/MgO multilayer film, they found that the orbital current at the Cu/MgO interface formed ultrafast charge currents via the inverse orbital Rashba-Edelstein effect.