Researchers at the Hebrew University of Jerusalem announced a significant breakthrough in light-magnetism interactions.
Impossible Connection
Harnessing light using magnetism, and vice versa could be a breakthrough for electronics, optics, and data storage. However, this has been impossible since magnetic fields and light do not normally interact with one another.
Since light is a form of electromagnetic radiation consisting of oscillating magnetic fields, it is expected to interact with magnetism. Light and magnetism do not recognize one another because light has a much higher frequency, oscillating 10,000 times faster than the fastest magnetic fields.
The interaction between a magnetic material and radiation is established when they are in perfect equilibrium. However, the situation where there is both radiation and magnetic material that are not in equilibrium has only been described very partially.
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Light-Driven Magnetic Control
Professor Amir Capua of the Institute of Applied Physics and Electrical Engineering made an unexpected discovery that reveals a mechanism where an optical laser beam controls the magnetic state in solids. The result of their study is discussed in the paper "Helicity-dependent optical control of the magnetization state emerging from the Landau-Lifshitz-Gilbert equation."
This previously unknown connection signals a major leap in our understanding of light-magnetism dynamics. It paves the way for light-controlled, high-speed memory technology, such as Magnetoresistive Random Access Memory (MRAM), and the development of innovative optical sensors.
The study challenges conventional thinking by decoding the overlooked magnetic aspect of light. This optical property usually receives less attention because of the slower response of magnets compared to the rapid behavior of light radiation.
It was found that the magnetic component of a rapidly oscillating light wave can control magnets, redefining the traditional principle of physical relations. The research team also identified the elementary mathematical relation that describes the strength of the interaction. From this discovery, they established the connection between the amplitude of the magnetic field of light, its frequency, and the energy absorption of the magnetic material.
The discovery is tightly connected to the realm of quantum technologies, combining principles from two scientific disciplines that so far had little overlap. According to Capua, they arrived at this realization by using principles that are well established within the quantum computing and quantum optics communities but less so in the fields of spintronics and magnetism.
The non-equilibrium regime is at the core of quantum optics and quantum computing technologies. From examining non-equilibrium regime in magnetic materials, researchers have underpinned the fundamental understanding of the response of magnets to the short time scales of light. The established interaction turns out to be very significant and efficient.
As noted by Capua, their findings can explain various experimental results that have been reported in the last two to three decades. Their discovery has far-reaching implications, especially in data recording that uses light and nano-magnets. It provides insight into the realization of ultra-fast and energy-efficient optically controlled MRAM and a shift in information storage and processing across diverse fields.
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