A team of physicists led by Dr. Yuan Lu of the Jean Lamour Institute at the University of Lorraine used electrical pulses to manipulate magnetic information into polarized signals. This discovery could revolutionize long-distance optical communications, including between Earth and Mars. This breakthrough involves the field of spintronics, which aims to manipulate the spin of electrons to store and process information.
Structure of SOT Spin LED: Control of emission intensity and charging current is the basis of information transfer and processing. In contrast, robust information storage and magnetic random access memory are implemented using carrier spins and their associated magnetizations in ferromagnets. The missing link between the respective fields of photonics, electronics, and spintronics is modulating the circular polarization of emitted light rather than its intensity through electrically controlled magnetization.Dynon other. demonstrated that this missing link is established in light-emitting diodes at room temperature in the absence of an applied magnetic field through the transfer of angular momentum between photons, electrons, and ferromagnets.Image credit: Dynon other., doi: 10.1038/s41586-024-07125-5.
Spintronics has been successfully used in magnetic computer hard drives, where information is represented by the direction of electron spin and its proxy, magnetization.
Ferromagnetic materials such as iron and cobalt have an unequal number of electrons, with their spins oriented either along or against the magnetization axis.
Electrons with spins aligned with the magnetization move smoothly in a ferromagnetic material, while electrons with spins in the opposite direction bounce. This represents binary information of 0’s and 1’s.
The resulting change in resistance is a key principle in spintronic devices, where magnetic states can be maintained indefinitely, which can be considered stored information.
Just as a refrigerator magnet requires no power to stick to a door, spintronic devices require much less power than traditional electronics.
But like pulling a fish out of water, when an electron is removed from a ferromagnetic material, the spin information is quickly lost and can no longer travel far.
This major limitation can be overcome by utilizing circularly polarized light, also known as helicity, as another spin carrier.
Just as humans used homing pigeons centuries ago to carry written communication farther and faster than on foot, the trick is to transfer the spin of an electron to a photo, a quantum of light. That’s probably true.
Such transfer is possible due to the presence of spin-orbit coupling, which causes spin information loss outside the ferromagnetic material.
The key missing link is to electrically modulate the magnetization and thereby change the helicity of the emitted light.
“The concept of spin LEDs was first proposed at the end of the last century,” Dr. Lu said.
“But to move into practical use, it must meet three important criteria: it must operate at room temperature, it does not require a magnetic field, and it must be able to be electrically controlled.”
“After more than 15 years of dedicated work in this field, our collaborative team has managed to overcome all obstacles.”
In their research, Dr. Lu and his colleagues succeeded in switching the magnetization of a spin injector using an electric pulse that uses spin-orbit torque.
The electron spin is rapidly converted into information contained in the helicity of the emitted photon, allowing seamless integration of magnetization dynamics and photonic technology.
This electrically controlled spin-to-photon conversion is currently realized with electroluminescence in light-emitting diodes.
In the future, through implementation in semiconductor laser diodes, so-called spin lasers, this highly efficient information encoding will pave the way for high-speed communication across interplanetary distances, since the polarization of light is preserved in spatial propagation. It is possible and could potentially make it possible. The fastest mode of communication between Earth and Mars.
It also has significant benefits for the development of a variety of advanced technologies on Earth, including photonic quantum communications and optical computing, neuromorphic computing for artificial intelligence, and ultra-fast and highly efficient optical transmitters for data centers and light-fidelity applications. will bring about.
“The realization of spin-orbit torque spin injectors is a decisive step in the development of ultrafast and energy-efficient spin lasers for next-generation optical communications and quantum technologies,” said Professor Nils Gerhardt of Ruhr University. ” he said.
team's work It was published in the magazine Nature.
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PA Dynon other. 2024. Optical helicity control by electromagnetic switching. Nature 627, 783-788; doi: 10.1038/s41586-024-07125-5
