The ability to manipulate magnetization on ultrafast time scales is crucial for advancements in various fields such as ultrafast magnetism, spintronics, and data storage technologies. While intense laser pulses have been traditionally used to induce magnetization changes in materials, the typical thermal effects limit the applicability of such techniques due to the heat load on the material. In a recent study by scientists from the Max Born Institute (MBI) and an international team of researchers, a non-thermal approach of generating large magnetization changes using circularly polarized extreme ultraviolet (XUV) radiation was demonstrated.
The Inverse Faraday Effect
The key mechanism behind this non-thermal manipulation of magnetization is the inverse Faraday effect (IFE). Unlike traditional thermal effects that rely on the absorption of light and subsequent heating of the material, the IFE is a direct and coherent interaction between the light’s polarization and the electronic spins in the material. When a material is exposed to circularly polarized XUV radiation, the IFE leads to the generation of magnetic moments in the medium, with the direction of magnetization dependent on the helicity of the circular polarization. This non-thermal pathway allows for efficient manipulation of magnetization without the substantial heat load associated with traditional methods.
To demonstrate the effectiveness of the non-thermal approach, the researchers used circularly polarized femtosecond pulses of XUV radiation generated at the free-electron laser FERMI. By applying these pulses to a metallic ferrimagnetic iron-gadolinium (FeGd) alloy, the scientists were able to observe significant IFE-induced magnetization changes. The high photon energy of the XUV radiation allowed for resonant excitation of core-level electrons, leading to large opto-magnetic effects in the material. Through experimental observations and supported by theoretical calculations and simulations, the researchers found that the IFE-induced magnetization could reach up to 20-30% of the ground-state magnetization of the alloy, showcasing the potential of this non-thermal approach.
The findings of this study have far-reaching implications for the fields of ultrafast magnetism, spintronics, and coherent magnetization control. By providing a method for the non-thermal generation of large magnetization changes on ultrafast time scales, this research opens up new possibilities for technological applications where fast repetition rates are required. Furthermore, the ability to manipulate magnetization using non-thermal pathways could lead to advancements in data storage technologies and the science of nonlinear X-ray matter interactions.
The study conducted by researchers from the Max Born Institute highlights the potential of non-thermal approaches for manipulating magnetization using light. By harnessing the power of the inverse Faraday effect, the researchers have demonstrated a novel method for generating large magnetization changes in materials without the drawbacks of traditional thermal effects. As research in this field progresses, the implications of non-thermal manipulation of magnetization are expected to drive innovations in various technological applications and scientific disciplines.
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