Detection of Very High Frequency Magnetic Resonance Could Revolutionize Electronics

upstart writes in with an IRC submission for Cowardly_Anonymizer:

Detection of very high frequency magnetic resonance could revolutionize electronics:

The finding, reported today in Nature, is based on a magnetic resonance phenomenon in anti-ferromagnetic materials. Such materials, also called antiferromagnets, offer unique advantages for ultrafast and spin-based nanoscale device applications.

The researchers, led by physicist Jing Shi of the University of California, Riverside, generated a spin current, an important physical quantity in spintronics, in an antiferromagnet and were able to detect it electrically. To accomplish this feat, they used terahertz radiation to pump up magnetic resonance in chromia[*] to facilitate its detection.

In ferromagnets, such as a bar magnet, electron spins point in the same direction, up or down, thus providing collective strength to the materials. In antiferromagnets, the atomic arrangement is such that the electron spins cancel each other out, with half of the spins pointing in the opposite direction of the other half, either up or down.

The electron has a built-in spin angular momentum, which can precess the way a spinning top precesses around a vertical axis. When the precession frequency of electrons matches the frequency of electromagnetic waves generated by an external source acting on the electrons, magnetic resonance occurs and is manifested in the form of a greatly enhanced signal that is easier to detect.

In order to generate such magnetic resonance, the team of physicists from UC Riverside and UC Santa Barbara worked with 0.24 terahertz of radiation produced at the Institute for Terahertz Science and Technology's Terahertz Facilities at the Santa Barbara campus. This closely matched the precession frequency of electrons in chromia. The magnetic resonance that followed resulted in the generation of a spin current that the researchers converted into a DC voltage.

[...] Shi, who directs Department of Energy-funded Energy Frontier Research Center Spins and Heat in Nanoscale Electronic Systems, or SHINES, at UC Riverside, explained subterahertz and terahertz radiation are a challenge to detect. Current communication technology uses gigahertz microwaves.

"For higher bandwidth, however, the trend is to move toward terahertz microwaves," Shi said. "The generation of terahertz microwaves is not difficult, but their detection is. Our work has now provided a new pathway for terahertz detection on a chip."

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